DDG 4.Nc3 Nf6

1.e4 e6 2.d4 d5 3.c4 dxe4 4.Nc3 Nf6! [Minev]. Now White's main idea is to play f3, the move typical to all Diemer gambits. It simply confirms the gambit, which, if accepted, allows White's other knight come to play with a tempo. Instead of playing 5.f3, White can also play a few other moves to avoid some unwanted lines. 5.Nge2 may be the only line where White has a totally different plan.

W	5.f3 (Main Lines) 5.Bg5 5.a3 5.Nge2 5.Be3 5.Various

5.Bg5

5.Bg5

A) 5...Be7

6.f3 exf3 (6...Nc6! is very good, and 7.Nge2 exf3 or 7.d5 exd5 8.Bxf6 Bxf6 9.cxd5 Nd4 10.Nxe4 O-O -/+ [Watson]) 7.Nxf3
- 7...b6 8.Bd3 (with good attacking prospects [Watson]) Bb7 9.O-O Nbd7 10.Qc2 c5 11.d5 exd5 12.cxd5 O-O 13.d6 Bxd6 14.Bxh7+ Kh8 15.Rad1 Qb8 16.Bf5 +/=, 1-0 in 23, Guala - Shainswit, 1958.
- 7...Nc6! -/+ [ECO], but Watson does not believe this after 8.Qd2! and 8...h6 9.Bf4 or 8...O-O 9.O-O-O (with the idea Bd3-b1, Qd3, h4 [Heikkinen]) or 8...e5 9.dxe5 Qxd2+ 10.Kxd2! unclear.
- 7...h6 8.Bf4 Nc6 9.Be2 Bb4 10.O-O Bxc3 11.bxc3 Bd7 12.Rb1 b6 13.Qc2 Qe7 14.Bxc7 Rc8 15.Bg3 Na5 16.Ne5 O-O 17.Bh4 g5 18.Rxf6 Qxf6 19.Nxd7 Qe7 20.Nxf8 Kxf8 21.Bg3 1-0, Wall - Asa1, Zone 1996.
6.Bxf6?! Bxf6 7.Nxe4 Qxd4 8.Nxf6+ Qxf6 9.Qd2 e5 10.O-O-O Nc6 11.Re1 O-O 12.Nf3 Bg4 13.Be2 Rad8 14.h3 Rxd2, Brown - Hornby, 1994.
6.Nge2 Nc6 (6...c5 =/+ [Watson]) 7.Qa4 O-O 8.O-O-O -/+ was analysed by Fritz 3.

B) 5...Nbd7 6.Nxe4 c6 7.Nf3 transposes to the Cambridge Springs Defence.

One transposition could be 1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.Bg5 dxe4 (French Defence, Burn Variation) 5.Nxe4 Be7 6.Bxf6 gxf6 7.Nf3 b6 8.Bd3 Bb7 9.O-O Nd7 10.c4 c6 11.Qe2, 1-0 in 23, Gdanski - Meyer, 1991.

C) 5...h6 6.Bh4 g5 7.Bg3 b6 8.f3 Bb7 transposes to game 1.d4 b6 2.c4 Bb7 3.Nc3 Nf6 4.Bg5 h6 5.Bh4 d5 6.f3 e6 7.e4 g5 8.Bg3 dxe4 9.h4 Bd6 10.Bf2 exf3 11.Nxf3 g4 12.Nd2 Nbd7 13.a3 c5 14.Nb5 Bf4 15.Qe2 a6 16.Nc3 cxd4 17.Bxd4 Bg3+ 18.Kd1 Qc7, 0-1 in 36, Guevera - Farleigh, Moscow 1994.

5.a3

5.a3

A) 5...Be7 6.f3

6...exf3 7.Nxf3 O-O 8.Bd3 b6 9.Bf4 Bb7 10.Qe2 a6 11.O-O-O Nbd7 12.g4 Re8 13.Rhf1 Nxg4 14.Ne5 Ngf6 15.Bxh7+ Kxh7 16.Nxf7 Qc8 17.Rg1 Bf8 18.Rd3 e5 19.dxe5 Nc5 20.Rh3+ 1-0 (20...Kg8 21.Nh6+ Kh8 22.Ng4+ Kg8 23.Nxf6+ Kf7 24.Qh5+ or 22...Nh7 23.Rxh7+!), Duhm - Martin, corr. 1908-1909. German Emil Josef Diemer (1908-1990) gives this game of Swiss Dr. Andreas Duhm (1883-1975) as the stem game of the DDG. By the way, looks like playing the DDG guarantees long life...
6...Nc6 7.Be3 exf3 8.Nxf3 Ng4 9.Bf4 Bd6 10.Bxd6 Qxd6 11.Qd2 O-O 12.Ne4 Qe7 13.h3 Nf6 14.Nxf6+ Qxf6 15.Bd3 g6 16.Be4, Diemer - Wotkowski, 1951.

B) 5...c5! -/+ [ECO] 6.Be3 cxd4 7.Bxd4 Be7 8.Be3 O-O 9.Qxd8 Rxd8 10.Nge2 b6 11.Ng3 Bb7 12.Be2 Na6 13.b4 Rd7 14.O-O Rad8 15.Nb5 Bc6 16.Nxa7 Rxa7 17.Bxb6 Rad7 18.Bxd8 Bxd8 19.b5, 1-0 in 47, Brause - blc, FICS 1996.

C) 5...Nc6 6.Be3 e5 7.dxe5 Qxd1+ 8.Rxd1 Nxe5 9.Nb5 Bd6 10.Rxd6 cxd6 11.Nc7+ Kd7 12.Nxa8 b6 13.Nxb6+, 1-0 in 24, Brause - MinoanPrince, FICS 1996.

5.Nge2

The king's knight on e2 became popular in the first DDG e-mail tournament. Especially the strongest players preferred this to f3, which hopes to get the knight on f3 with a tempo. Brause has also played Nge2 a lot. Quite often White manages to win the sacrificed pawn back, which, however, sounds an odd plan: why play the gambit in the first place if material is so important.

5.Nge2

A) 5...Nc6 6.g3 (very original 6.b3 Bb4 7.Bb2 was suggested by Chessmaster 3000) Bb4 7.Bg2 Bxc3+ 8.bxc3 O-O 9.Bg5 (9.O-O b6 10.Bg5 a5 11.Bxe4, 1-0 in 26, Wall - Holsapple, 1982) h6 10.h4?! hxg5 11.hxg5 g6? 12.gxf6 Qxf6 13.Bxe4 Kg7 14.Nf4 Rd8 15.Qh5 Ne7 16.Qh6+ Kg8 17.Nh5 1-0, Clark - Rossiter, 1996.

B) 5...Bb4

6.Bg5 h6 7.Bxf6 Qxf6? (7...Bxc3+ =) 8.Qa4+ Nc6 9.d5, 1-0 in 25, Angus - Purdy, corr. 1996.
6.g3
- 6...O-O 7.Bg2 Nc6 8.O-O e5 9.d5 Bxc3 10.bxc3 Na5 11.Bg5 Nxc4 12.Bxe4 Nd6 13.Bg2 h6 14.Bc1 Bf5 15.Qb3 b6 16.c4 Nfe4 17.a4? (17.Be3) and White went to blunder his queen in 4 moves, 0-1 in 21, Heikkinen - amiel, Zone 1996.
- 6...b6?? 7.Bg2? (7.Qa4+ Nc6 8.Qxc6+ Bd7 9.Qb7 a5 10.Bf4! +/-) Bb7 8.O-O O-O 9.Bg5 Be7 10.Bxf6 Bxf6 11.Nxe4, 0-1 in 36, Heikkinen - maxs, Zone 1996.

C) 5...b6!? 6.Bg5 Bb7 7.d5 exd5 8.cxd5 Bc5 9.Nxe4 Nxe4?? 10.Qa4+ (10.Bxd8?? Bxf2#) Qd7 11.Qxe4+ Kf8 12.Nc3 f6 13.Bf4 Kf7 14.Bb5 c6 15.dxc6 Nxc6 16.O-O Qe6 17.Bc4 1-0, Brause - Chamaco, FICS 1997.

D) 5...c5 6.d5 exd5 7.cxd5 Bd6 8.Nxe4 Nxe4 9.Qa4+ Nd7 10.Qxe4+ Qe7 11.Qxe7+ Kxe7 12.Nc3 Nb6 13.Bd3 Re8 14.O-O g6 15.Re1+ 1-0, Brause - CME, FICS 1997.

5.Be3

5.Be3

A) 5...Nc6

6.h3 Bb4 7.a3 Bxc3+ 8.bxc3 h6 9.f3 O-O 10.Qc2 exf3 11.Nxf3 Bd7 12.Bd3 Qe7 13.O-O Rfd8, 1-0 in 25, Heikkinen - GNU WebChess, 1995 .
6.g3!? Bb4 7.Bg2
- 7...Bxc3+ 8.bxc3 O-O 9.f4 exf3 10.Nxf3 Qe7 11.O-O Rd8, 1-0 in 35, Heikkinen - Chessmaster 3000, 1995.
- 7...O-O 8.f3 exf3 9.Nxf3 (9.Bxf3 e5!) Ng4 10.Bg1! (10.Bg5 f6 11.Bc1 e5) Qd6!? seems playable.
6.Qd2 Bb4 7.a3 Bxc3 8.Qxc3 e5 9.dxe5 Ng4 10.Bf4 Bf5 11.h3 Nh6 12.Bxh6 gxh6 13.f4 Qe7 14.O-O-O Rd8 15.Rxd8+ Kxd8 16.g4 Bd7 17.Bg2 f5 18.exf6 Qe8 19.f7 +-, 1-0 in 29, Heikkinen - zeff, Zone 1996.
6.f3 transposes.

B) 5...Bb4 6.Qc2

6...c5! 7.O-O-O Bxc3? (7...Qa5) 8.Qxc3 cxd4 9.Bxd4 Nbd7 10.f3 (10.g4!?) exf3 11.Nxf3 Qc7 12.Bd3 b6 13.Ne5 Nc5 14.Rhf1 Bb7 15.Qc2? (15.Bc2!) O-O-O 16.Bc3 Nxd3+, draw in 39, Heikkinen - Sahlberg, 2000.
6...Nc6 7.O-O-O O-O 8.Nxe4 Re8 9.f3 Bf8 10.Ne2 Nb4 11.Qb1 c6 12.N2c3 Qe7 13.a3 Na6 14.Bd3, 1-0 in 41, Hardman - Hughes, 1991.
6...Bxc3+ 7.Qxc3 Ng4 8.Bf4 e3 9.fxe3 O-O 10.h3 Nf6 11.g4? Ne4 12.Qc2 Qh4+ 13.Ke2 1-0, Heikkinen - Villaseñor, Zone 1997. Black lost on time, otherwise the game could have continued 13...Qf2+ 14.Kd3 Na6 15.Qxf2 Nxf2+ 16.Ke2 Nxh1 17.Bg2 -/+.
6...O-O 7.O-O-O Bxc3 8.Qxc3 b5!? (novelty) 9.cxb5 a6 10.Kb1 Nd5 11.Qd2 axb5 12.Bxb5 Nxe3 13.Qxe3 Qd5 14.Qb3 Qxb3 15.axb3 Rd8 16.Ne2 Bb7 17.h4 Ra5 18.Bc4 Nc6 19.h5 Rf5 20.h6 Rxf2 21.hxg7 Na5 22.Ng3 Nxc4 23.bxc4 e3 24.Rhe1 Rd2 0-1, Heikkinen - Tanti, DDGA 1997.

6.Qb3 Qe7 7.a3 Ba5?? 8.Qa4+ Nc6 9.b4 Bb6 10.c5 1-0, Brause - mega, FICS 1997.

C) 5...Be7 6.f3 exf3

7.Nxf3 O-O 8.Bd3 Nbd7 9.O-O Re8 10.Ng5 Nf8 11.Bc2 b6 12.Qf3 Rb8 13.Be4 +/-, Heikkinen - Smith, corr. 1996.
7.Qxf3!? O-O 8.O-O-O c5 9.d5 exd5 10.cxd5?? (10.Nxd5) Bg4, 0-1 in 14, Heikkinen - Evans, corr. 1997.

After the modest 5...Be7, White has a wide range of choices:

6.Be2 O-O 7.Nh3!? Nbd7 8.O-O b6 9.Qb1 Bb7 10.Ng5 c5 11.b3 cxd4 12.Bxd4 Nc5 13.Rd1 Qc7 14.Bxc5 Bxc5 15.Ncxe4, draw in 37, Brause - DNAgene, FICS 1997.
6.Nge2 b6 7.Qc2 Bb7 8.O-O-O followed by Ng3 =.
6.Qc2 Nc6 7.O-O-O Nb4!?.

D) 5...b6

6.Qc2 Bb7 7.Nge2 Nbd7 8.O-O-O c5 9.Ng3 cxd4 10.Bxd4 Qc7 =, draw in 26, Heikkinen - Walkenhorst, corr. 1996-1997.
6.f3 Bb7 7.fxe4 Nxe4 8.Nxe4 Bxe4 9.Qg4 Bg6 10.h4 unclear.
6.c5 and 6.d5 have been played by Brause.

The following ADG games and lines where c4 and Nc3 are deferred have similar ideas to this DDG line:

1.e4 e6 2.d4 d5 3.Be3 dxe4 4.f3 Nf6

5.a3 Bd6 6.c4 b6 7.Nc3 Bb7 8.fxe4 Nxe4 9.Nf3, 1-0 in 20, Morgado - Pancaldo, 1971 .
5.fxe4 Nxe4 6.Bd3 Nf6 7.Nf3 b6 8.O-O Bb7 9.c4 Nbd7 10.Nc3 Be7 11.Qe1 Ng4 12.Rd1.

E) 5...c6 6.f3 exf3 7.Qxf3 Qa5 8.O-O-O Nbd7 9.g4 h6 10.h4 (10.Bd3) Bb4 11.Nge2 Nb6 12.c5 Nbd5 13.Nxd5 Nxd5 14.Kb1 Bd7 15.Ng3 O-O-O 16.Ne4 Kb8 17.Bf2 Qa4 18.Bd3 f6 19.a3 Bxa3 20.Bc2 Qb4 21.Qxa3 Qxa3 22.bxa3 f5 23.Bg3+ Ka8 24.Nd6 Nc3+, draw in 39, Heikkinen - Bye, corr. 1998.

Various

5.g4?! h6 6.h3 c6 would transpose to this Caro-Kann DDG game: 1.d4 c6 2.e4 d5 3.c4 dxe4 4.g4?! Nf6 (4...e5! -/+) 5.h3 h6 6. Nc3 e6 7.Bg2 Bb4 8.Ne2 c5 9.dxc5 Qxd1+ 10.Kxd1 Bxc3 11.Nxc3 O-O 12.Nxe4 Rd8+ 13.Kc2 Nxe4 14.Bxe4 Nc6 15.Bxc6 bxc6 16.b4 a6 17.Bb2 Rb8 18.Rad1 Bd7 19.a3 f6 20.Rd6 +/-, 1-0 in 32, Heikkinen - Villaseñor, Zone 1996.