N) 4....Nxe4 5.Qxd4 Nf6 6.Nc3 Be7
     7.Bg5 c6 8.O-O-O d5 9.Qh4

N1) 9....O-O N3) 9....Qa5
N2) 9....Nbd7 N4) 9....Be6!

Position after 9.Qh4

   The Queen gets out of the way of the Rook at d1 (creating tactical possibilities with the Rook facing Black's Queen at d8) and vacates the d4 square for the Knight at f3. The Queen move, combined with the idea of leaving the Bishop at c4 for as long as possible, was first tested by Schlechter at the turn of the last century and refined by Heinkinheimo in the 1950s. It is now preferred in master practice over 9.Rhe1 followed by Bd3 (note that the Bishop at c4 is still immune after 9.Rhe1 since 9....dxc4?? 10.Qxd8#).

Index of Lines
A) 1.e4 e5 2.Bc4 Nf6 3.d4 ...
B) 3.d4 Nxe4 4.dxe4
C) 3.d4 exd4 4.Nf3 ... 
D) 4.Nf3 Bb4+
E) 4.Nf3 d6
F) 4.Nf3 c5
G) 4.Nf3 Bc5
H) 4.Nf3 d5
I) 4.Nf3 Nxe4 5.Qxd4 ...
J) 5.Qxd4 Nf6 6.Bg5?!
K) 5.Qxd4 Nf6 6.Nc3! ...
L) 6.Nc3 Be7 7.Bg5 Nc6 8.Qh4 d5
M) 6.Nc3 Be7 7.Bg5 Nc6 8.Qh4 d6
N) 6.Nc3 Be7 7.Bg5 c6 8.O-O-O d5
Urusov Gambit & Related Links
Urusov PGN File from Pitt Archives

   The Rook move generally transposes to the main lines, however, and most of the games given here actually had the more traditional move order. One well known game went rather differently: 9.Rhe1 Be6 10.Bd3 Qa5 11.Kb1 (11.Bf5!) 11....Nbd7 12.Ne5 c5? 13.Qh4 Ne5 14.Re5 O-O-O 15.Bd2 Qc7?! (15....Qb6] 16.Nb5! Qe5 17.Bf4 Qh5 18.Na7+ Kd7 19.Bb5# Fahndrich--Steinitz, Vienna 1897. Also of interest is the game Monkman-Chessmaster4000, London 1995, which went 9.Rhe1 Be6 10.Bd3 c5?! 11.Qa4+! Nc6 12.Bc4! dxc4?! 13.Rxd8+ +=.

   While this is the most contested line of the Urusov Gambit, it is also the one where White has achieved the best results. Black's central build up (with 7....c6 and 8....d5) appears too slow, and his seemingly stable center often crumbles beneath the force of White's initiative. Black does best to delay castling and the main line follows N4 with 9....Be6 10.Rhe1 Nbd7, when White can choose between the tricky 11.Nd4!? and the standard 11.Bd3. The Knight move seems most forceful, but the Bishop move has been most analyzed. Marco Bulgarini's recent innovation in the N4a3b line may put 11.Nd4!? Nc5 12.f4?! into question, so White should transpose to N4b7 with 12.Bd3!. An interesting alternative plan for White was tried successfully in the game Voigt--Mephisto, suggesting that there is still room for innovations in these lines. As always, you are urged to trust your own analysis.

N1) 9....O-O

N1a) 10.Bd3

N1a1) 10....Nbd7? 11.Bxh7+ Nxh7 12.Bxe7 Qc7 13.Bxf8 Ndxf8 14.Rhe1 +- Heikenheimo--Kongshavn, Dubrovnik 1950

N1a2) 10....g6 11.Rhe1 Be6 12.Nd4 Nbd7 13.Rxe6 fxe6 14.Nxe6 Qe8 15.Nxf8 Qxf8 16.Re1 Re8 17.f4 +- Shamkovich

N1a3) 10....h6 11.Bxh6 (11.Rhe1!?) 11....Ne4 12.Qf4 Bd6 13.Qe3 Bc5 14.Qf4 (14.Nd4 Bxd4 15.Qxd4 gxh6 16.Bxe4 Qg5+ 17.f4 Qxf4+ 18.Kb1 dxe4 19.Nxe4 Nd7 20.Rhf1 20.Rhf1 Qxh2 21.Rd3 c5 22.Qf2 Qe5 23.Qh4 Re8 24.Rg3+ Kf8 25.Rgf3 Re7 26.Qxh6+ Qg7 27.Qh5 Ne5 28.Rg3 Bg4 29.Qh4 Nc4 0-1 Monk--Wharrier, Correspondence 1995) 14....Bd6 15.Qe3 Nxc3 (15....Bc5) 16.bxc3 Re8 17.Qg5 Qxg5+ 18.Bxg5 Bg4 19.h4 Nd7 20.h5 f6 21.Be3 Bc5 22.Bxc5 Nxc5 23.h6 Nxd3+ 24.Rxd3 gxh6 25.Rxh6 Kg7 26.Rh4 Bf5 27.Rd1 Re2 28.Rd2 Re4 = Fedorov--Barbitsky, St. Petersburg 1999.

N1b) 10.Rhe1

N1b1) 10....h6? 11.Bxd5! Nbd7 (11....hxg5 12.Nxg5 +-; 11....cxd5 12.Rxe7! +-) 12.Bc4 b5 13.Bd3 hxg5 14.Nxg5 Re8 15.Bh7+ Kf8 16.Bf5 Kg8 17.Nxf7 Kxf7 18.Be6+ Kg6 19.f4 Nh5! 20.Qg4+ Kh6 20.Qg4+ Kh6 21.Bf7?! (21.Bf5!) 21....Nxf4 22.Re6+ Kh7 23.Ne4 Ne5 24.Qxf4 Bxe6 25.Rxd8 Nxf7 26.Rxa8 Rxa8 27.Qc7 Re8 28.Qxc6 Nd6 29.Nxd6 Bg5+ 30.Kb1 Bd7 31.Qc3 Re3 32.Qd2 Re5 33.Qd3+ Bf5 34.Qg3 Rd5 35.Qf3 Be6 36.Nxb5 Re5 37.Qg3 Bf4 38.Qf2 Bg5 39.Nd4 Be3 40.Qh4+ Kg6 41.Nxe6 Rxe6 42.a4 Kf5 43.Qh5+ g5 44.h4 Re4 45.Qf7+ Ke5 46.h5 Rh4 47.Qg7+ Kf5 48.h6 Bd4 49.g4+ 1-0 Schlechter--Neustadtl and Tietz, Carlsbad 1901.

N1b2) 10....Nbd7 11.Bd3 g6 (11....h6 12.Bxh6 gxh6 13.Qxh6 Bd6 14.Re3 Qc7 15.Qg5+ Kh8 16.Ne5! Nxe5 17.Qxf6+ Kg8 18.Rg3+ Ng6 19.Bxg6 1-0 Wober--Druckenthaner, Austria 1988) 12.Re2 (12.Nd4!? Re8 13.Nf5 Bf8 14.Nh6+ Kg7 15.Bf5 Be7 16.f4 b5 17.Re3 b4 18.Ne2 Bc5 19.Rxe8 Qxe8 20.Ng3 Ng8 21.Nh5+ gxh5 22.Re1 Be3+ 23.Kb1 Nf8 24.Bxc8 Qxc8 25.Rxe3 Ng6 26.Qxh5 Qa6 27.Nf5+ Kh8 28.b3 1-0 Oberhofer--Wokurka, Correspondence 1995) 12....Re8 13.Rde1 Ne4 14.Nxe4 dxe4 15.Rxe4 f6 (15....Bxg5+ 16.Nxg5 +-) 16.Bc4+ Kg7 17.Qxh7+ Kxh7 18.Rh4+ Kg7 19.Bh6+ Kh7 20.Bf8# Larry Evans

N1b3) 10....Bf5

N1b3a) 11.Nd4?! Bg6 12.Bd3

N1b3a1) 12....Qd7?! 13.f4! (13.Bxg6?! fxg6! [13....hxg6? 14.Rd3-Rh3 ±] 14.Ne6 Re8 15.Rd3 Bc5! =+ [15....h6? 16.Nxg7!!]) 13....h6! 14.Bxh6! gxh6 15.Bxg6 fxg6 16.Qxh6 Kf7? (16....Bb4! 17.Qxg6+ Qg7 18.Qxg7+ Kxg7 19.Ne6+ Kf7 20.Nxf8 Kxf8 is highly unclear) 17.Ne6?! (17.Nf3! +- due to the double threat at g5 and e5) 17....Rg8! 18.g4 ± Qd6 19.Ne4 Nxe4 20.Rxe4 Bf8 21.Ng5+ Kf6 22.Qh4 Qd7 23.Ne6+ Kf7 24.Ng5+ Kf6 25.Re5 Na6 26.Ne4+ Kg7 27.Qf6+ Kh7 28.Ng5+ Kh6 29.Ne6 Kh7 30.Nxf8+ 1-0 Zarske--Schneider, Correspondence 1993

N1b3a2) 12....h6! 13.Bxg6 hxg5 14.Qxg5 fxg6?! (14....Ne4! 15.Bh7+ Kxh7 [15....Kh8!? 16.Qh5 Nf6 17.Qh4 Ne4 18.Qh3 Ng5 =] 16.Qh5+ Kg8 17.Nxe4 dxe4 18.Ne6 fxe6 19.Rxd8 Bxd8 =+ according to Lauterbach) 15.Ne6 Ne4?! (15...Qd7 16.Qxg6 Rf7 17.Ng5 Bd6 =+) 16.Qxg6 Bg5+ 17.f4 Qf6 18.Qxf6 Bxf6 19.Nxe4 dxe4 20.Nxf8 Kxf8 21.Rxe4 += Na6 22.g4 Nc5 23.Re2?! (23.Rc4! ±) 23....Na4 24.c4 Nb6 25.g5 Be7 26.Re4 Kf7 27.h4 Rh8 28.Rh1?! (28.g6+! Kf8 29.a4! ±) 28....Rh5 = 29.b3 Nc8 30.Re5 g6 31.c5 Bf8 Caro--Janowski, Berlin 1897, 1/2-1/2 in 81 moves.

N1b3b) 11.g4!?
This move is certainly playable, but may not yield White a clear advantage. Download my PGN file bf5.pgn for complete analysis.

N1b3b1) 11....Bd7? 12.Rxe7!? (12.Bd3! h6 13.Bxh6 Ne4 14.g5! gxh6 15.Rg1 Nxc3 16.Bh7+ Kxh7 17.Qxh6+ Kg8 18.g6 1-0 Mercurio--Schneider, Correspondence 1996) 12....Qxe7 13.Bd3 h6 14.Bxh6 gxh6 15.Qxh6 Re8 16.Ng5 Qf8 17.Qxf6 Qg7 18.Qf4 Na6 19.Nh7 f5 20.gxf5 Nc5 21.f6 Nxd3+ 22.Rxd3 Qxh7 23.Rg3+ Kf7 24.Rg7+ Qxg7 25.fxg7+ Kg8 26.Qh6 ± Rac8 27.Ne2 Re7 28.Nf4 Rxg7 29.Nh5 Rg1+ 30.Kd2 Bf5 31.Ng3 Bd7 32.Qg6+ Kf8 33.Qd6+ Ke8 34.Nh5 Bh3 35.Nf4 Bd7 36.h4 Rg7 37.h5 Rf7 38.h6 1-0 Morper--Grajetzky, Correspondence 1987.

N1b3b2) 11....Bg6 12.Ne5 (not 12.Bxd5? cxd5 13.Rxe7 Qxe7 14.Nxd5 Qc5 -+) 12....Qc7! (12....Bb4?! 13.Nxg6 fxg6 [13....hxg6 14.Re3 +-] 14.Nxd5! cxd5 15.Bxf6 Qxf6 16.Bxd5+ followed eventually by Bxb7 ±)

N1b3b2a) 13.Bb3!? (Muller and Voigt say White has an attack here) 13....Bd8!! (Max Burkett's "refutation" when I analyzed this move with him last summer. Not 13...Re8?! 14.Nxg6! fxg6 [14...hxg6? 15.Re3 +-] 15.Bxf6 gxf6 16.Rxd5! Kg7 17.g5!! [17.Rd2!? f5 18.Qh3 +=] 17...fxg5 18.Qd4+ Bf6 [18...Kh6 19.Re3! Qxh2 [19...Qc8 20.Rde5 Rd8 21.Qe4 Bf6 22.h4!!] 20.Qe5! Qf4 21.Ne2±] 19.Qxf6+ Kxf6 20.Rxe8 Qxh2 21.Rd6+ Kf5 22.Be6+ Ke5 23.Rd2 a6 24.f4+ Qxf4 25.Bc8+ Kf6 26.Rf8+ Ke5 27.Rxf4 gxf4 28.Rd8 Nd7 29.Re8+ Kd6 30.Ne4+ Kd5 31.Bxd7 Rxe8 32.Nf6+ Kd6 33.Bxe8 Ke7 34.Nxh7 Kxe8 35.Ng5 Ke7 36.Nh3 Kf6 37.Nxf4 Kf5 38.Nd3 +-) 14.f4!? Nbd7 (14...h6 15.Bxh6 Ne4 16.g5 Nxc3 17.Bxg7 Kxg7 18.Qh6+ Kg8 19.Re3 Bxg5 20.fxg5 Nxd1 21.Ng4 f6 22.Qxg6+ Qg7 23.Nxf6+ Rxf6 24.Qxg7+ Kxg7 25.gxf6+ Kxf6 26.Kxd1 =) 15.Nxd7 Nxd7 (15...Qxd7!?) 16.f5 Bxg5+ 17.Qxg5 f6 18.Bxd5+ cxd5 19.Nxd5 Qd8 20.Ne7+ Qxe7 21.Rxe7 fxg5 22.Rdxd7 unclear, but probably better for Black in the long run. Download my PGN file bf5.pgn for complete analysis.

N1b3b2b) 13.Nxg6!? fxg6 (13....hxg6? 14.Re3! +-) 14.Rxd5!! cxd5 15.Nxd5 Qxc4 16.Nxe7+ Kf7 (16....Kh8? 17.Nxg6+ Kg8 18.Nxf8 +=) 17.Bxf6 Nbd7 (17....Qxa2?! 18.g5! +=; 17....h6? 18.Nf5!? or 18.Bc3!; 17....Nc6 18.Nxc6 =) 18.Bc3 Rae8 19.Qxh7 unclear. Download my PGN file bf5.pgn for complete analysis.

N1b3c) 11.Bd3!? Bxd3 12.Rxd3 (12...Nbd7 13.Nd4 Bc5 14.Nf5 Re8 15.Rxe8+ Qxe8 16.Nxg7 Qe1+ 17.Nd1 Bxf2 18.Qf4 +=) 13.Bxh6 gxh6 14.Rxe7 Qxe7 15.Nd4 Qe1+ 16.Nd1 Nh7 17.Re3 Qb4 18.Qg3+ (18.Rg3+ Kh8 19.Qg4 Ng5 20.Qh4=) 18...Ng5 19.Nf5 d4 0–1 Klueber - Oller, Correspondence 1995 20.Nxh6+! Kh8 21.Qxg5 dxe3 22.Qf6+ Kh7 23.c3± Müller and Voigt

N1b4) 10....Be6 11.Bd3 (11.Nd4!?) 11....h6

N1b4a) 12.Kb1!? Nbd7 13.g4! Nc5 14.Bxh6 Nfe4 15.g5 Nc3 16.bxc3 Nxd3 17.Rxd3 gxh6 18.Qxh6 +- Voigt--Mephisto Computer, Dortmund 1992.

N1b4b) 12.Bxh6 Ne4

N1b4b1) 13.Qf4 Bd6 (13....Nxf2 14.Bxg7 Nxd3+ 15.Rxd3 Kxg7 16.Rxe6 fxe6 17.Qg4+ Kh7 18.Qh5+ Kg7 19.Rd4 Rg8 20.Rg4+ Kf6 21.Qh6+ Kf7 22.Ne5+ 1-0 Medak--Hopper, Baile Herculane 1994) 14.Qe3 Bc5 15.Nd4 (15.Qf4 Nxc3? 16.Bxg7 Nxa2+ 17.Kb1 Kxg7 18.Qg3+ Kh8 19.Re5 Nc3+ 20.bxc3 Bg4 21.Rg5 Qb6+ 22.Kc1 Bxf2 23.Qxg4 1-0 Lemiex--Mary, Correspondence 1990) 15....Qf6 (15....Nxc3? 16.Bxg7!) 16.Be4 Qh6 17.Qxh6 gxh6 18.Bf3 Bd7 = Estrin

N1b4b2) 13.Qh5!

N1b4b2a) 13....Nxf2 14.Bg5 Nxd3+ 15.Rxd3 Nd7 16.Bxe7 Qxe7 17.Ng5 Nf6 18.Qh4 Qc7 19.Rf1 Rfe8 20.Rxf6 gxf6 21.Qh7+ Kf8 22.Nxe6+ Rxe6 23.Qh8+ Ke7 24.Qxa8 b5 25.h4 (25.g3 b4 26.Nd1 Qb6 27.h4 Re1 28.h5 Rh1 29.h6 f5 30.Qh8 f4 31.gxf4 1-0 MChess 5.0--Genius 2, Van Leeuwen Tournament Nieuwegein 1997) 25....Kd7 26.Qg8 Qf4+ 27.Kb1 Qxh4 28.Qxf7+ Re7 29.Qg6 Re1+ 30.Nd1 Kc7 31.g3 Qh1 32.Qg7+ Kb6 33.Kc1 Rf1 34.Qf8 a5 35.Qb8+ Ka6 36.Qc7 Qh6+ 37.Kb1 f5 38.a4 b4 39.Qc8+ Ka7 40.Qd7+ Kb8 41.Qd8+ Kb7 42.Qxa5 Qh5 43.Qxb4+ 1-0 MChess 5.0--Genius 1, Van Leeuwen Tournament Nieuwegein 1997

N1b4b2b) 13....g6 14.Qe5 Bf6 15.Qf4 Nxc3 Estrin 16.Rxe6 fxe6 17.Qg4 Rf7 (17....Nxa2+ 18.Kb1 Rf7 19.Kxa2 Kh8 20.Qxg6 Qg8 21.Qh5 += or 18....Nc3+ 19.bxc3 +=) 18.Qxg6+ Bg7 19.Bxg7 (19.Qh7+ Kf8 20.Qh8+ Ke7 21.Bg5 Bf6 22.Bxf6+ Rxf6 23.Qg7+ and White's attack continues with unclear play according to Van der Tak) 19....Rxg7 20.Qxe6+ Kh8?! (20....Kf8! 21.bxc3 +=) 21.Qh6+ (21.bxc3 +=) 21....Kg8 22.Bf5!? Nxd1 23.Be6+ Kf8 24.Qh8+ Ke7 25.Qxg7+ Kd6 (25....Kxe6 26.Ng5+ +-) 26.Qe5+ Kc5 27.Kxd1 (+- Van der Tak) 27....Kb6 28.Qd4+ Kc7 29.Qf4+ Qd6 30.Qxd6+ Kxd6 31.Bf5 Nd7 32.g4 Ne5 33.Ng5 Ke7 34.b3 Rf8 35.h4 Rxf5 36.gxf5 Kf6 37.f4 Ng4 38.Ke2 Nh6 39.h5 Nxf5 40.Kd3 Nh4 41.h6 Ng6 42.Ke3 c5 43.c4 d4 44.Kf3 b6 45.Ne4+ Kf7 46.f5 Nf8 47.Ng5+ Kg8 48.f6 Ng6 49.Ke4 Nh8 50.h7+ Kf8 51.b4 a5 52.bxc5 bxc5 53.a4 Ng6 54.Ne6+ Kf7 55.Kf5 1-0 Luebke--McMahon, IECG Correspondence 1996.

N2) 9....Nbd7 10.Rhe1

N2a) 10....dxc4? 11.Bxf6 gxf6 12.Ne4! (12.Nd4!? Qa5 13.Ndb5! Kd8 14.Qc4 cxb5 15.Qf7 Re8 16.Nxd5 +- Shamkovich) 12....O-O 13.Ng3 Kh8 14.Nf5 Bc5 15.Qh5 c3 (15....Re8 16.Nh6! Lane) 16.Re4 Qb6 17.b3 Rg8 18.Qxf7 Qa5 19.Rxd7! Ba3+ 20.Kb1 Qxf5 21.Re8 1-0 Avrukh--Skripchenko, Linares 2001

N2b) 10....Kf8?! 11.Bxd5! cxd5 (11....Nxd5 12.Nxd5 Bxg5+ 13.Nxg5+- van der Tak) 12.Rxe7! Qxe7 (12....Kxe7 13.Qb4+ +-) 13.Nxd5 Qe4 14.Bf4! h6? (14....Qe6!? 15.Kb1! [15.Nc7 Qxa2 16.Bd6+ Kg8 17.Nxa8 Qa1+ 18.Kd2 Qxb2 unclear] 15....Qc6 [15....Qg4 16.Bd6+ Kg8 17.Ne7+ Kf8 18.Re1! Qxh4 19.Nxc8+ Kg8 20.Ne7+ Kf8 21.Nxh4 +-] 16.Be5! a5 [16....Nxe5? 17.Qb4+ +-] 17.Bxf6 Nxf6 18.Nxf6 +- Shamkovich) 15.Bd6+ Kg8 16.Ne7+ Kf8 (16....Kh7 17.Ng5#) 17.Nxc8+ Ke8 18.Re1 Qxe1+ 19.Nxe1 Rxc8 20.Qd4 Kd8 21.Nd3 Re8 22.Be5 (22.Qxa7! van der Tak) 22....Re6 23.f4 a5 24.c3 Ke8 25.Qa4 (25.f5! van der Tak) 25....b6 26.Qd4 Kf8 27.g4 Rce8 28.Kc2 Kg8 29.a4 R8e7 30.h3 Ne8 31.Qd5 Nxe5 32.fxe5 Nc7 33.Qc4 Rd7 34.Qe4 Nd5 35.c4 Ne7 36.Qa8+ Kh7 37.Qe8 Rc7 38.Qxf7 Rxc4+ 39.Kb1 Rcc6 40.h4 Ng6 41.h5 Nxe5 42.Qf5+ g6 43.hxg6+ Nxg6 44.Nf4 Re1+ 45.Ka2 Kg7 46.Nh5+ Kg8 47.Qd7 Re7 48.Qxc6 +- Kreiman--Shirazi, New York 1992.

N2c) 10....Nb6 11.Bxf6 gxf6 12.Bd3 Be6 13.Nd4 Qd7 14.Bf5 Bxf5 15.Qxf6 += Shamkovich.

N3) 9....Qa5 10.Rhe1 Be6 (10....dxc4? 11.Bxf6 gxf6 12.Qxf6 +-) 11.Nd4!? (11.Bd3 Nbd7 12.Nd4 O-O-O 13.Nxe6 fxe6 14.Rxe6 Bb4 15.Ne2 Rde8 16.Rxe8+ Rxe8 17.Kb1 h6 18.Be3 += Miraglia-Perrotta, IECG 1997) 11....Nbd7 (11....dxc4 12.Nxe6 fxe6 13.Rxe6 and now 13....Rf8 14.Rde1 Rf7 14.Qh5+!! g6 15.Rxe7+ Kxe7 16.Bxf6+ Kxf6 17.Qxa5 +- or 13....Kf7 14.Rde1 Bd8 15.Qxc4! Qxg5+ [15....Kg6 16.R1e5 +-] 16.f4 Qg4 17.h3! Qf5 [if the Queen surrenders control of e6, there follows 18.Rxf6++! Kxf6 19.Qe6#] 18.Re7+ Kg6 19.Qf7+ Kh6 20.Qxg7+ Kh5 21.g4+ +-) 12.Nxe6 fxe6 13.Rxe6 Kf7 14.Rde1?! (14.Nxd5!! +-) 14....Rae8?! (14....Bb4! +=) 15.Be2! Bd8 (15....Ke6 16.Bh5+ Kd6 17.Qg3+ Reinfeld) 16.Bg4 Nxg4? (16....d4! +=) 17.Qxg4 Bxg5+ (17....Nf6 18.Bxf6 Bxf6 19.Rxf6+ Kxf6 20.Qf4+ Kg6 21.Qd6+ Kh5 22.g4+ +- Reinfeld) 18.Qxg5 Nf6 (18....Rxe6 19.Qf5+ Rf6 20.Qd7+ Kg6 21.Re3 +- Reinfeld) 19.Rxf6+! 1-0 Heinkinheimo--Crepaux, Dubrovnik 1950 (19....gxf6 20.Qh5+).

N4) 9....Be6 10.Rhe1 (The move 10.Nd4!? should eventually transpose to the main line below, because White cannot leave out Rhe1 indefinitely without allowing Black the Nfe4! shot. For example, 10.Nd4 Nbd7 11.Bd3 Nc5 12.Bf5?! Nfe4! 13.Nxe4 Nxe4 14.Bxe7 Qxe7 15.Qxe7+ [15.Qf4 Qg5!] 15....Kxe7 16.Nxe6 fxe6 [or 16....Nxf2!] 17.Bxe4 dxe4 18.Rhe1 Rhf8 19.Rd2 Rad8 =+) 10....Nbd7 (10....O-O transposes to N1 above)

N4a) 11.Nd4!??
This move may be put into question by N4a3b2 below. White should use it only as a tricky way of transposing to the N4b line after 11.Nd4 Nc5 12.Bd3!

N4a1) 11....dxc4? 12.Nxe6! (12.Rxe6? fxe6 13.Nxe6 Qa5 14.Nxg7+ Kf7 15.Rxd7! Nxd7 16.Qh5+ Kg8! -+) 12....fxe6 13.Bxf6 Bxf6 (13....gxf6 14.Rxe6 Rg8 15.Qxh7 Rxg2 16.f4 b5 17.Rde1 Ne5 18.Ne4 c3 19.bxc3 c5 20.fxe5 f5 21.Qxf5 Kd7 22.Nxc5+ Bxc5 23.Rd1+ Kc7 24.Qh7+ Qe7 25.Rxe7+ Bxe7 26.Qxe7+ Kb6 27.Rd6+ Ka5 28.Qc7+ Ka4 29.Ra6+ 1-0 Dufek--COMP Rebel 8, Usti 1997) 14.Rxe6+ Kf8 15.Qf4 Rc8 (15....Qb8 16.Qf5 Nb6 17.Rdd6 Qc7 18.Rxf6+ gxf6 19.Rxf6+ Ke8 20.Re6+ Qe7 21.Rxe7+ Kxe7 22.Qe5+ Kf7 23.Qc7+ Kf8 24.Qxb7 Rg8 25.g3 Rg7 26.Qxc6 1-0 COMP MChess 4.0--COMP Genius 2.0, Euro-Chess K 1995) 16.Ne4 Qc7 17.Qf5 Kg8 18.Re7 Bxe7 19.Rxd7 h6 20.g3 c3 21.Qe6+ Kh7 22.Qxe7 cxb2+ 23.Kxb2 Qxd7 24.Qxd7 Rhf8 25.f4 Rcd8 26.Qe7 Rb8 1-0 COMP Chess Pro 3.5--COMP Chessmaster 4000, Faas 1994.

N4a2) 11....Nf8 12.Nf5 Bxf5 13.Bxf6 Be6 14.Bxe7 Qxe7 15.Qd4 Qf6 16.Qe3 O-O-O?! 17.Qxa7 Qf4+ 18.Re3 Qxc4 19.Qa8+ Kc7 20.Qa5+ Kd7 21.Ne4 Ke8 22.Nc5 Qf4 23.Nxb7 Rc8 24.Qa3 Ng6 25.g3 Qxf2 26.Nd6+ Kd7 27.Ne4 Qf5 28.Qd6+ Ke8 29.Nc5 Ne7 30.Rde1 1-0 Schlechter--Teichmann, Vienna 1904.

N4a3) 11.....Nc5 12.f4?
Better is probably 12.Bd3!, transposing to the main line below. Notice that with the Knight at d4, rather than at f3, the Bishop at g5 is underprotected in some lines. White plays 12.f4 here in part to defend the Bishop because Black threatened to play 12...Nfe4! But Black appears to have two good lines of defense.

N4a3a) 12....Nfd7 13.Bxe7 Qxe7 14.Qxe7+ (14.Qg3?! dxc4 15.f5 O-O [15....O-O-O? 16.Ndb5! +-] 16.fxe6 fxe6! =+) 14....Kxe7 15.b4?! (15.Bf1 Kf6 [15....g6 16.g4] 16.b4 Bg4! =+) 15....dxc4 16.f5 Na6 =+ 17.fxe6 Nb6 18.exf7+ Kxf7 19.Rf1+ Kg6 20.Nf3 h6 21.Ne5+ Kh7 22.Rf7 Rhe8 23.Nf3 Nxb4 24.Rxb7 N4d5 25.Nxd5 Nxd5 26.Nd4 Ne3 27.Re1 c5 28.Nf3 c3 29.Rc7 c4 30.Rd7 Nxg2 31.Rg1 Re2 32.Nd4 Rf2 33.Ne6 Rg8 34.Rc7 Ne3 35.Nxg7 Kh8 36.Re7 Rxc2+ 0-1 Wapner--Lukacs, Budapest 1997.

N4a3b) 12....O-O! (Black does best to get his King off of the e-file immediately) 13.Bd3 (The Bishop could stay at c4, but it will eventually need to reposition for an attack on the castled King. Now White threatens 14.Bxh7+ because the Bishop at e7 is loose. Alternatives seem less good. Attacking with 13.f5!? Bd7! 14.Bxd5? works well if Black plays 14....Nxd5? 15.Bxe7 += or 14....cxd5? 15.Rxe7! Qxe7 16.Nxd5! +-, but it seems to lose after 14....h6! when White has two pieces in the lurch. Also bad is 13.b4?! h6! 14.bxc5 hxg5 15.fxg5 Nh7! =+. Perhaps White should try 13.f5!? Bd7! 14.Rxe7!? Qxe7 15.Bxd5 h6 16.Bxf6 Qxf6 17.Qxf6 gxf6 18.b4!? with some play for the exchange.) 13....Re8 (The Rook challenges White's control of the e-file and protects the Bishop at e7 while clearing the f8 square for Bf8 or Kf8 to defend in certain lines. Notice that White cannot play 14.Bxf6? Nxd3+! followed by 15....Bxf6 -+. Bulgarini notes that the immediate 13....Nxd3+ 14.Rxd3 Re8 15.f5 Bd7 is unclear, while after 13....h6 14.Bxh6 Nfe4 15.Qh5 Qc8 16.f5!) 14.Bf5?!

N4a3b1) 14....Bxf5? 15.Nxf5 Ncd7 16.Rd3 g6 += 17.Nxe7+ Rxe7 18.Rf1 b5 19.f5 b4 20.Nd1 Re4 21.g4 Rxg4 22.Qxg4 Nxg4 23.Bxd8 Rxd8 24.Rd4 Nde5 25.h3 Nh2 26.Rf2 Nhf3 27.Rxb4 Ng5 28.Rg2 Ne4 29.Rb7 Nd6 30.Re7 Nd7 31.fxg6 hxg6 32.Re3 Nf5 33.Ra3 Ra8 34.Ra6 c5 35.Nc3 Nb6 36.a4 d4 37.Ne4 c4 38.Nf6+ Kg7 39.a5 Na4 40.Re2 Rd8 41.Re8 Rd6 42.Rxd6 Nxd6 43.Rd8 Nb7 44.Ne8+ Kf8 45.Ra8 Nxa5 46.Nc7+ 1-0 Tseitlin--Lev, ICPO 1990.

N4a3b2) 14....h6! 15.Bxh6 (White must sacrifice the Bishop since both 15.b4? hxg5 16.fxg5 Bxf5! 17.Nxf5 Nfe4! and 15.Re3? hxg5 16.fxg5 Bxf5 17.Nxf5 Nfe4! -+ are losers.) 15...gxh6 16.Bxe6 (White cannot improve with 16.Qxh6 Bf8 17.Qg5+ Bg7 18.Nxe6 Nxe6 19.Bxe6 Rxe6 20.Rxe6 fxe6 -+ or 16.Qg3+ Kh8 17.b4 Ng8 18.bxc5 Bh4 19.Qf3 Bxe1 20.Rxe1 Qf6 -+ according to Bulgarini's analysis. Müller and Voigt say that "an ocean of complications" follow 16.b4, but Bulgarini also shows that White is clearly worse after 16.b4 Nh7 17.Qg4+ Kh8 18.bxc5 Bf6 19.Bxe6 Qa5 20.Re3 fxe6 -+. I think Bulgarini's novelty puts the whole 11.Nd4 line in doubt.) 16....Nxe6 17.Nxe6 fxe6 18.Rxe6 Kf7 19.f5 Bf8 20.Rde1 Bg7 21.Qg3 Rxe6 22.fxe6+ Kg8 23.a3 Qe7 24.h4 Rf8 25.Kb1 Ne8 26.h5 Rf6 27.Qg4 Nc7 28.Qh4 Nxe6 29.Qg4 Qd6 30.Nd1 Qf4 31.Qxf4 Nxf4 32.g4 Re6 33.Re3 Rxe3 34.Nxe3 Kf7 0-1 Serramidigni-Bulgarini, ICCF 2001-2003.

N4b) 11.Bd3!
This move is most often played here and is probably best, given Bulgarini's innovation in the N4a line above.

N4b1) 11....Qa5 12.Nd4 O-O-O 13.Nxe6 fxe6 14.Rxe6 Bb4 15.Ne2 Rde8 (15....h6 16.Bxf6 Nxf6 17.Kb1 Bd6 18.Nd4 1-0 Estrin--Klaman, USSR Ch. 1946; 15....Bc5 16.Kb1 Qb6 17.f3 Bf2 18.Qh3 Kb8 19.Re7 g6 20.Qe6 c5 21.Qxb6 axb6 22.Bb5 h6 23.Bf4+ Kc8 24.Nc3 d4 25.Ne4 Nxe4 26.fxe4 1-0 Tronhjem--Granberg, Dorrespondence 1985.) 16.Rxe8+ Rxe8 17.Kb1 h6 18.Be3 += Bc5 19.Bg6 Re7 20.Nd4 Bxd4 21.Qxd4 c5 22.Qd3 Qc7 23.g3 d4 24.Bf4 Qc6 25.Bf5 Ne4 26.f3 Nf2 27.Qc4 b5 28.Qg8+ Kb7 29.Rf1 g5 30.Bc1 Qxf3 31.Qd8 1-0 Miraglia--Perrotta, IECG Correspondence 1998.

N4b2) 11....Qc7 12.Nd4 Nf8 13.f4 O-O-O 14.f5 c5 15.Ndb5 Qa5 16.fxe6 fxe6 17.Rxe6 Nxe6 18.Bf5 Kb8 19.Bxe6 d4? 20.Bf4+ Ka8 21.Nc7+ Kb8 22.N3b5 Bd6 23.Nxd6 1-0 Nicolai--Engert, Bamberg 1968.

N4b3) 11....Qb6 12.Nd4 O-O-O 13.Nxe6 fxe6 14.Rxe6 Bb4 15.Ne2 (15.Nb5 Muller and Voigt) 15....Bc5 16.Bxf6 Nxf6 17.Bf5 Kb8 18.Qg3+ Qc7 19.Qxc7+ Kxc7 20.Nd4 Rde8 21.Rxe8 Rxe8 22.Ne6+ Kd6 23.Nxc5 Kxc5 24.f3 Re2 25.Rg1 Kd4 26.Bd3 Rf2 27.Rd1 Ke3 28.Bf1 c5 29.b3 Kf4 30.a4 b6 31.Re1 h5 32.h3 h4 33.Ba6 Rxg2 34.Re7 Kxf3 35.Rxa7 Ke3 36.Rb7 Rg3 37.b4 Kd4 38.Rxb6 c4 39.Kb2 Rxh3 40.a5 Ne4 41.Bc8 Rg3 42.Rb8 Nc3 43.Bd7 Rg1 44.Rg8 Nd1+ 45.Ka2 Kc3 46.a6 Kxb4 47.Rb8+ Kc5 48.a7 Nc3+ 49.Kb2 d4 50.Rb5+ Kd6 51.Rd5+ Nxd5 52.a8=Q c3+ 53.Kb3 Rb1+ 54.Ka2 Rb2+ 55.Ka3 1-0 Nathe--Walther, Correspondence 1975.

N4b4) 11....c5 12.Ne5 Nxe5 13.Rxe5 d4 14.f4 Nd7 15.Bb5 Bxg5 16.fxg5 Qc7 17.Bd7+ Kd7 18.Qe4 Qc6 (Not 18....b6 19.Nb5 Qc6 20.Nd4! with a strong attack for White, but 18....Rad8 19.Nd5 Qd6 20.c3 Kc8 is a better try) 19.Rxc5! Qe4 (19....Qxc5 20.Qb7+ Kd6 21.Ne4+ +-) 20.Ne4 Rhc8 += 21.Rd4+ Ke7 22.a4 b6 23.Rc8 Rc8 24.Kd2 Bf5 25.c4 Rc6 26.Ng3 Be6 27.Kc3 Rc5 28.h4 h6 29.b4 Rc8 30.Ne4 f5 31.Nf2 hg5 32.hg5 Rh8 33.Nh3 Bd7 34.b5 Rh5 35.Kb4 Rh8 36.a5 Be6 37.a6 Bf7 38.Kc3 g6 39.Kb4 Rc8 40.Nf4 Rc5 41.Nd3 Rc8 42.c5 bc5+ 43.Nc5 Be8 44.g3 Rc7 45.Rd1 Rc8 46.Re1+ Kd6 47.Nb7+ Kd7 48.Re3 Bf7 49.Rd3+ Ke7 50.Rc3 Rc3 51.Kc3 Bd5 52.Kd4 Bg2 53.Kc5 Bf1 54.Na5  1-0 Timoshenko--Karpov, USSR 1967.

N4b5) 11....Nf8 12.Nd4 Ng8 13.Bxe7 Nxe7 14.f4 g6 15.Qf6 Rg8 16.g4 Qd6 17.f5 gxf5 18.Bxf5 Qf4+ 19.Kb1 Qg5 20.Qe5 O-O-O? 21.Ndb5! 1-0 Blosze--Carstens, Correspondence 1984.

N4b6) 11....Ng8 12.Bxe7 Qxe7 13.Qg3 g6 (13....Kf8 14.Nd4 g6 15.f4 Nh6 16.f5 Nxf5 17.Bxf5 gxf5 18.Nxf5 += Cibulka--Fichtl, Pardubice 1965) 14.Nd4 Ngf6 (14....O-O-O? 15.Ncb5! Ndf6 16.Na7+ Kd7 17.Nab5 +-) 15.f4 Nh5 16.Qe3 Qf6 17.f5 gxf5 18.Bxf5 Ng7 19.g4! 1-0 Firv--Kolojanu, Correspondence 1965.

N4b7) 11....Nc5 12.Nd4
(12.Bf5?!! Bxf5 13.Bxf6 Ne6 14.Bxe7 Qxe7 15.Nxd5!?? cxd5 16.Qa4+ Kf8 17.Rxd5 Bg6 18.Rd7 Qc5 19.Ne5 Rc8? [19....Qxf2!] 20.Rxf7+! Kg8 [20....Bxf7 21.Nd7+ Ke7 22.Nxc5 Rxc5 23.Qxa7 Rhc8 24.Qxb7+ R8c7 25.Qb4 +=] 21.Nxg6 hxg6 [21....Kxf7? 22.Qd7+] 22.Rf3 Rxh2 23.Rc3 Qg5+ 24.f4! Qd8 25.Qb3 Rxc3 26.Qxe6+ Kf8 27.bxc3 Rxg2 28.Rd1 Qc7 29.Rd7 [29.f5! Estrin] 29....Qxf4+ 30.Kb2 Qf6 31.Qc4 Qb6+ 32.Qb4+ Qxb4+ 33.cxb4 b5 34.Rxa7 g5 35.a4! bxa4 36.b5 Rg4 37.c3 Rg2+ 38.Ka3 Rg1 39.Ka2 Rg2+ 40.Ka3 Rg1 41.b6 1-0
Estrin--Khachaurov, Moscow 1943; 12.Kb1!? Nfd7 13.Qg3 Bf6 14.h4 h6 15.Be3 Qa5 16.Bd4 O-O-O 17.Bxf6 gxf6 18.Qf4 Nxd3 19.Rxd3 Rdg8 20.g3 Rg4 21.Qd6 Nc5 22.Rd4 Ne4 23.Qe7 Rgg8 24.Rb4 Qa6 25.Nxe4 dxe4 26.Nd4 Re8 27.Qc5 Bxa2+ =+ Zavanelli-Cordeiro, North Atlantic Correspondence 1985) 

N4b7a) 12....h6 13.Bf5
(not 13.Nf5?! Kd7! or 13....Nxd3+ 14.Rxd3 Bxf5 15.Bxf6 Be6 16.Rxe6!? fxe6 17.Qh5+ Kd7 =+; but playable is 13.f4!? Nxd3+ 14.Rxd3 O-O 15.Nxe6 fxe6 16.Bxf6 Bxf6 17.Qg4 e5 18.fxe5 Bh4 19.Qe6+ Kh8 20.g3 = Lautenbach--Steinman, Correspondence 1994, which may deserve more attention given Harding's suggestion below of meeting 13.Bf5 with 13....Rg8! unclear)

N4b7a1) 13....O-O 14.Bxh6 Nfe4 15.Qg4 Bg5+ 16.Bxg5 Qxg5+ 17.Qxg5 Nxg5 18.h4 Bxf5 19.Nxf5 Nge6 20.b4 Nd7 21.h5 Nf6 22.h6 g6 23.Nd4 Nxd4 24.Rxd4 Rfe8 25.Rxe8+ Rxe8 26.g4 += Hartnak--Brewer, 1993.

N4b7a2) 13....Nh7 14.Bxe7 Qxe7 15.Qxe7+ Kxe7 16.b4 Na6 17.Bxe6 fxe6 18.Nxe6 Kd7 19.b5 Nc7 20.Nc5+ Kc8 21.Re7 g6 22.bxc6 bxc6 23.N3e4 Ne8 24.c4 dxe4 25.Ne6 Ng7 26.Rc7+ Kb8 27.Rxg7 Ng5 28.Nd8 Kc8 29.h4 Rh7 30.Rg8 Kc7 31.hxg5 +- Zedtler--Wilhelmi, 1999.

N4b7a3) 13....Qd7 14.b4? (14.Nxe6! Nxe6 [14...fxe6 15.Na4! Nxa4 16.Bxe6 Qd6 17.Bxf6 Bxf6 18.Qxa4 Kd8 19.c4! d4 20.g3 +=] 15.Qh3 Qc7 16.Bxf6 Bxf6 17.Bxe6 fxe6 18.Qxe6+ Kf8 19.Kb1 +=) 14....O-O-O 15.Nxe6?! fxe6 16.bxc5 exf5 17.Bxf6 Bxf6 18.Qb4 Bxc3 19.Qxc3 Rhe8 20.Qa5 Kb8 21.Qc3 Re4 22.f3 Re7 23.Re5 Rde8 24.f4 g5 25.g3 Rxe5 26.fxe5 f4 27.gxf4 gxf4 28.Qd4 Qf5 29.Re1 f3 30.Qe3 Re6 31.Kd2 Kc7 32.Rf1 Rxe5 33.Qxf3 Qg5+ 34.Kd3 0-1 Granat--Brustman, 1980.

N4b7a4) 13....Rg8! (Harding's suggestion in Kibitzer 83. I think this is the strongest new idea he sets forth in his article and so I've decided to publish a direct response.) 14.Bd2! (Harding gives instead 14 Bxf6 Bxf6 15.Qg4 Bxd4 16.Qxd4 Qd6 17.Na4 [17.Bh7?! Rh8 18.Qxg7 O-O-O 19.g3 Qe7! =+] 17....Nxa4 18.Qxa4 Kd7 19.Bxe6+ fxe6, which he rather generously calls equal [=+ more like].) 14....Nfe4 (The only challenging move based on my analysis.) 15.Nxe4! (Harding has discussed the same basic sacrifice in Kibitzer 33, so it is surprising that he doesn't consider this himself. Not 15.Qf4!? Nxc3! -- though Max Burkett points out here that 15....Bg5?! 16.Qg4 Bxd2+ [16...Nxd2? 17.f4; 16...Nxf2 17.Bxg5 Qxg5+ 18.Qxg5 hxg5 19.Rd2 +=] 17.Rxd2 Nxd2 18.Nxe6 fxe6 19.Bxe6 Nxe6 20.Rxe6+ Kd7 21.Rf6+ Kc7 22.Rf7+ Kb8 23.Nb5 cxb5 = [23...Qg5? 24.Qxg5 hxg5 25.Nd6] is a draw.) 15....Nd3+ (This looks strongest, as it was in Harding's previous analysis.) 16.cxd3 Bxh4 17.Nc5 g6 (Less good is 17....Qb6 18.Ndxe6 fxe6 19.Bg6+! Ke7 20.Rxe6+ Kd8 21.d4 Rf8 22.g3! with a strong plus for White) 18.Ndxe6 (18.Bxe6 =) 18....fxe6 19.Rxe6+ Be7 (19....Kf7? 20.Nxb7! leads to some pretty variations) 20.Bxg6+! (20.Rde1 gxf5 21.Nxb7 Qc7 22.Nd6+ Kd8 23.Ba5 [23.Nf7+!? Ke8! [23....Kc8? 24.Rxe7 Qxh2 25.g3! +-] 24.Nd6+ Kd8 =) 23....Qxa5 24.Nb7+ Kc8 25.Nxa5 Bb4 26.Rxc6+ Kd7 27.Re5 Bxa5 28.Rxh6 Bb6 29.Rxd5+ Ke7 = and White should probably take the repetition by 30.Re5+ etc.) 20....Rxg6 21.Rxg6 Kf7 22.Ne6 Qb6 23.Rg7+ Kxe6 24.Re1+ Kf6 25.Rgxe7 (25.Rexe7 Qc5+ 26.Bc3+ d4 27.Rgf7+ = draw by perpetual check) 25....Rg8 (25...Qc5+ 26.Bc3+ d4 27.R1e6+ +- Burkett) 26.g3 and White has at least equal chances if not better in this unbalanced position. Max Burkett suggests 26....Qc5+ 27.Kd1! (27.Bc3+ d4 =) 27...Qxe7 28.Rxe7 Kxe7 29.Bxh6 += since White's three connected passed pawns create "great practical chances." In any case, White should not be worse here.

N4b7b) 12....Nfd7

N4b7b1) 13.f4!? Bxg5 14.fxg5 Nxd3+ 15.Rxd3 Nc5 16.Rh3 a5 17.Qh5! += Kd7 18.Rhe3 b5 19.Nce2 Ne4 20.Nxe6 Kxe6 21.Nc3 f5 22.gxf6 Qxf6 23.Nxe4 dxe4 24.Rxe4+ Kd6 25.Qd1+ Kc5 26.Re5+ Kb6 27.Qd4+ Ka6 28.Qc5 Rac8 29.Re7 Rc7 30.Rxc7 Qf4+ 31.Kb1 Qxc7 32.Re7 Qb6 33.Qxb6+ Kxb6 34.Rxg7 Rf8 35.b3 Rf2 36.h4 h5 37.g3 Rg2 38.a3 Kc5 39.Kb2 Kd4 40.Rg5 c5 41.Rxh5 Rxg3 42.Rh8 c4 43.Rd8+ Kc5 44.Rc8+ Kd4 45.bxc4 bxc4 46.Ra8 Rh3 47.Rxa5 Rxh4 48.c3+ Ke4 49.a4 Rh2+ 1/2-1/2 Prokes--Spielmann, Vienna 1907.

N4b7b2) 13.Bxe7 Qxe7 14.Qxe7+ Kxe7 15.f4 Nxd3+ 16.Rxd3 (16.cxd3!? Polugaevsky) 16....Nc5 (16....g6 17.g4 Nc5 18.f5 [18.Rde3 Kd6 19.b4 Ne4 20.Nxe4 dxe4 21.Nxe6 fxe6 22.Rxe4 1-0 Nejstadt--Volkevich, Moscow 1958] 18....Nxd3+ 19.cxd3 Kd6 20.fxe6 Rae8 21.Nf3 fxe6 22.d4 Rhf8 23.Re3 a6 24.Na4 Rf4 25.Nc5 Re7 26.h3 a5 27.Nd3 Re4 28.Kd2 b6 29.Nf2 Rxe3 30.Kxe3 c5 31.Nd3 1-0 Neimann--Macles, FRA 1989) 17.Rde3 g6 18.b4 Na6 19.Nxe6 fxe6 20.Rxe6+ Kd8 21.Re7 d4 22.Na4 b6 23.a3 Nc7 24.Rg7 Ne8 25.Rge7 Nd6 26.R1e6 Re8 27.Rxe8+ Nxe8 28.Rxc6 Ke7 29.Nb2 Nf6 30.Rc7+ Ke6 31.Nd3 a6 32.Rg7 Kf5 33.h3 h5 34.Re7 Ne8 35.Re5+ Kf6 36.Rd5 Ke6 37.Rxd4 Nd6 38.g4 hxg4 39.hxg4 Re8 40.Nf2 1-0 Hausner--Weber, Policka 1992.

N4b7c) 12....Kf8 13.Bf5 Qd7 14.Re5 Re8 15.Rde1 Bd8 16.b4 Bxf5 17.Rxe8+ Nxe8 18.bxc5 f6 19.Bf4 Ba5 20.Qg3 Be4 21.Bd2 Bg6 22.h3 Kf7 23.Qb8 a6 24.Nce2 Qc7 25.Qa7 Bxd2+ 26.Kxd2 Qa5+ 27.Nc3 Qb4 28.Nxc6 Qf4+ 29.Kd1 Be4 30.Qxb7+ Nc7? 31.Nxe4 dxe4 32.g3 1-0 Marshall--Tholfsen, New York 1924 .

N4b7d) 12....Kd7 13.f4? (13.Bf5! h6 14.Bf4! g5 15.Qh3 gxf4 16.Bxe6+ fxe6 17.Nxe6 Nxe6 18.Qxe6+ Kc7 [18...Ke8? 19.Qxf6 +-] 19.Qxe7+ Qxe7 20.Rxe7+ Nd7 21.Ne2 Raf8 22.c4 += and I like White's chances in the ending.) 13....h6 14.Bxf6?! (Slightly better is 14.f5 hxg5 15.Qxg5 Nfe4 16.Qxg7 Nxc3 17.bxc3 Qg8 18.Qe5 Bd6 19.fxe6+ fxe6 20.Qe3 Rxh2 =+) 14....Bxf6 15.Qf2 Nxd3+ 16.Rxd3 g6 17.Ne4 b6 18.f5 gxf5 19.Nxf5 Rg8 20.c4 Rg4 21.g3 Be5 22.h3 Rxe4 23.Rxe4 Qg5+ 24.Ne3 Bxg3 25.Qf3 Rd8 26.Kc2 Ke8 27.cxd5 cxd5 28.Nxd5 Rxd5 29.Qxg3 Rc5+ 30.Kd1 Qc1+ 31.Ke2 Rc2+ 32.Kf3 Qf1+ 33.Ke3 Re2+ 34.Kd4 Qf6+ 35.Qe5 Qd8+ 36.Kc3 Qc8+ 0-1 Lepre--Nyffenegger, Correspondence 1992.

N4b7e) 12....Ng8!

N4b7e1) 13.Bxe7 Qxe7 (13....Nxe7 14.Nxe6 Nxe6 15.f4 Qd6 16.g3 h6 17.f5 Ng5 18.Qg4 Qf6 19.h4 Nh7 20.Qb4 b6 21.Nxd5! cxd5 22.Bb5+ Kf8 23.Rxd5 a6 24.Rd6 1-0 Barnard--Steadman, Correspondence 1997) 14.Qg3 g6 (14....Qf6 15.Ndb5 [or 15.Be2!? Nh6 16.Bf3 Rd8 17.b4 Na6 18.b5 Nc5 19.bxc6 bxc6 20.Qc7 += as in Burkett-Fester, IECG 1998] 15....Nxd3+ 16.Rxd3 cxb5 17.Nxd5 Qh6+ 18.Kb1 1-0 Grolehans--Knorr, Correspondence 1989; 14....Nf6? 15.Nf5 Qf8 16.Qc7 Rd8 17.Rxe6+ Nxe6 18.Qxb7 g6 19.Qxc6+ Rd7 20.Qc8+ Nd8 21.Re1+ Ne4 22.Nxe4 gxf5 23.Nd6# 1-0 Zavanelli--Pope, Correspondence 1987)

N4b7e1a) 15.f4?! Nh6 (15....O-O-O?! 16.f5 Nxd3+ 17.Rxd3 gxf5 18.Rde3 Qc7 19.Qg7 Ne7 20.Rxe6 fxe6 21.Nxe6 Rdg8? 22.Qxh8! Qxh2 23.Qf6 Ng6 24.Qxf5 Qh6+ 25.Kb1 Qh4 26.Nc5+ Kb8 27.Qe6 Rg7 28.Qd6+ 1-0 Lux--Wittenberger, Wuettemberg 1988) 16.Qe3 (Perhaps better 16.Be2 or 16.Bb5!?) 16....O-O-O! =+ (I don't see a good try for White here. Estrin gives "16....Qf6 17.f5 with attacking chances for White," but better is 17.Be2! += since 17.f5? Nxd3+! =+. Also strong for Black, though, is 16....Qd6! =+, so this line does not seem to hold up to close scrutiny.)

N4b7e1b) 15.b4 Nxd3+ 16.Rxd3 Nf6 17.Qh4 O-O 18.Rde3 Rae8 19.Nxe6 (19.f4?! Nh5 =+ Estrin--Byhovsky, Moscow 1964) 19....fxe6 20.Rxe6 = Van der Tak

N4b7e1c) 15.Nce2!? O-O-O 16.Nf4 Nh6 17.Nfxe6 fxe6 18.Qh3 Nxd3+ 19.Rxd3 Nf5 20.Nxf5 gxf5 21.Qxf5 Rhf8 22.Rxe6 Rxf5 23.Rxe7 Rxf2 24.Rb3 Rg8 25.Rbxb7 1/2-1/2 Navone--Gobel, Correspondence 1989

N4b7e1d) 15.Ndb5

N4b7e1d1) 15....Kf8 (15....cxb5? 16.Nxd5! +- wins) 16.b4! (16.Nc7 Rc8 17.Nxe6+ Nxe6 18.f4 Qf6 19.Rf1 Nh6 20.Qf3 Nc5 21.g4 Nxd3+ 22.Rxd3 Qh4 23.h3 Re8 24.f5 = Wallinger--Sieberg, Correspondence 1987) 16....Nxd3+ 17.Rxd3 Nf6 18.Qe5 Kg7 19.Rf3 cxb5?! (19....h5 Schafer) 20.g4 h6 21.h4 Rae8 22.g5 Qd8 23.Rxf6 Kh7 24.h5 Rhg8 25.Rh1 d4 26.hxg6+ Rxg6 27.Rxh6+ Kg8 28.Rfxg6+ 1-0 Schafer--Trzeciak, Correspondence 1985

N4b7e1d2) 15....Rd8! 16.Nc7+ Kf8 17.Nxe6! (17.Kb1?! Qd6 18.Nxe6+ Nxe6 19.Qh4 Qf4 20.Qxf4 Nxf4 21.Bf1 =+ Sasata--Webb, IECG 1997) 17....Nxe6 18.Ne2 Qd6 19.Qh4 Kg7 20.f4 was unclear in Daubenfeld--Fabrici, Correspondence 1997.

N4b7e2) 13.f4! Bxg5! (Not 13....Kf8? Torre--Tholfsen, New York 1924 when White should have played 14.b4! Nxd3+ 15.Rxd3 += or 13....h6?! 14.Bxe7 Qxe7 15.Qg3 g6 16.Bxg6! += as in Burkett-Grazinys, IECG 1998-2000) 14.fxg5

N4b7e2a) 14....Ne7 (Byhovsky, Pachmann, Larsen)

N4b7e2a1) 15.b4?! Nxd3+ 16.Rd3 Ng6 17.Qg4 O-O 18.Nxe6 fxe6 19.Qxe6+ Kh8 20.Rg3 Rf4 =+ Byhovsky

N4b7e2a2) 15.Nxe6 Nxe6 (on 15....fxe6 White can choose among 16.Na4, 16.g6, and 16.Bxh7!? with at least equal play) 16.g6? (Max Burkett sees this as an error and thinks best is 16.Re2! g6 [forced] 17.Rf1 += leading to advantage, as he demonstrates in extensive analysis. Thanks Max!) 16....Nxg6 17.Rxe6+ fxe6 18.Bxg6+ Kd7 19.Qg4 Qe7! 20.Be4 h5 21.Qg3 Qf6! 22.Bf3? (22.Bg6 h4 23.Qg4 Kc7 =+ Burkett) 22....h4 -+ in Burkett--Mascioni, IECG 1999, 0-1 in 43 moves.

N4b7e2b) 14....h6

N4b7e2b1) 15.Bf5?! Qxg5+ 16.Qxg5 hxg5 17.Nxe6?! (17.b4!?) 17....Nxe6 18.Bxe6 fxe6 19.Rxe6+ Kf7 =+ Galberg-Lund--Moller, Correspondence 1994.

N4b7e2b2) 15.Bg6?! Kd7?! (The Bishop move is so pretty that it's a shame to admit 15....Qxg5+! 16.Qxg5 hxg5 17.Nxe6 Nxe6 18.Rxe6+ Kf8 19.Rf1 Nf6 =+ is clearly better for Black: likely this was out of the range of any pre-1998 computer since it takes over 10-ply to see that Black is better) 16.Bxf7 (16.b4 Na6 17.Bxf7 Bxf7 18.Qg4+ Kc7 19.g6 Nf6 20.Qg3+ Kc8 21.gxf7 Qf8 22.Nf5 Ne4 23.Rxe4 dxe4 24.Nd6+ Kc7 25.Ncb5+ Kb6 26.Qe3+ c5 27.a4 Kc6 28.Nc4 Qe7 29.Qxe4+ Qxe4 30.Rd6# 1-0 COMP CM32 King2--COMP MachIII, SSDF 1993.) 16....Bxf7 17.Qg4+ Kc7 18.Qf4+ Kb6 19.Qxf7 Qxg5+ 20.Kb1 Qf6 21.Nxd5+! cxd5 22.Qxd5 Rc8 23.Re6+ Nxe6 24.Qb3+ Kc7 25.Nxe6+ Kb8 26.Qg3+ Ka8 27.Nc7+ Rxc7 28.Qxc7 a5 29.Rd8+ Ka7 30.Qb8+ Ka6 31.Rd6+ Qxd6 32.Qxd6+ b6 33.Qd3+ b5 34.a4 Nf6 35.axb5+ Kb7 36.Qf3+ Ka7 37.Qc6 Kb8 1-0 Monkman-Hiarcs3 COMPUTER, London 1995.

N4b7e2b3) 15.Re5!? Qd6 (Perhaps Black can improve here with 15....Qc7 or some other move) 16.Rde1 O-O-O

N4b7e2b3a) 17.Nxe6?! fxe6! (Now that the King is castled this is safe to play.) 18.h3 Ne4 =+ Elsborg--Nicolaisen, Correspondence 1987.

N4b7e2b3b) 17.g6! Nf6 18.gxf7 Nxd3+ 19.cxd3 Bxf7 20.Nf5 +=

N4b7e2b4) 15.Nxe6 Nxe6 (15....fxe6?! 16.Nxd5! Nxd3+ 17.Rxd3 cxd5 18.Rxe6+ Kf7 19.Re5 +=) 16.Re5 (16.Nxd5?! cxd5 unclear in an old correspondence game A. Giertz-Kornetzky, according to Harding, but I don't see White's attack after 17.Bb5+!? Kf8! 18.Rxe6!? Qxg5+! =+; 16.Bg6?! Qxg5+! =+) 16....Qd6! (16....Qe7? 17.Qh3 O-O-O 18.g6! ±; 16....Ne7? 17.g6! Nxg6 18.Qxd8+! Kxd8 19.Bxg6 ±) 17.Rde1 O-O-O! (17....Kf8 18.g6! -->) 18.Qf2! hxg5 (18....d4 19.Qxf7 Nxg5 20.Qxg7 dxc3! 21.Qxh8 Nf7 22.Qg7 cxb2+ 23.Kb1! Nxe5 24.Qxe5 Qxe5 25.Rxe5 +=/= and I like the Bishop better than the Knight here) 19.Qxf7 Nf4! 20.Qxg7! is unclear, but I like White's chances.




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