DDG
Kmoch Variation 4.Nc3
Nf6
5.f3
Bb4
In practice this is the most common move, transposing to the
NimzoIndian Defence Kmoch Variation.
Being the most famous current player of 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4
4.f3, super GM Shirov must have taken at least a sharp look on the
position arising after 4...d5 5.e4?! dxe4.
Like in most DDG variations, Black again intends to play c5,
demolishing the center. Therefore, White should immediately attack the
bishop.
W


6.Qa4+ Nc6 7.Be3
 7...Bd7 8.Qc2 exf3 9.Nxf3 OO 10.Bd3
(10.OOO Bxc3 11.bxc3 Qe7 would transpose to
Heikkinen  Rebel Decade, 1995)
h6
(10...Re8 11.OO with play for the pawn
[Schwarz])
11.OO Ng4 12.Bf4 Bd6 13.Bxd6 cxd6 14.a3 Qb6 15.Na4 Qa5 16.Rae1
(16.b4) Nxd4!, 01 in 30,
Heikkinen  maxs, Zone 1996.
 7...exf3 8.Nxf3 Ne4 9.Qc2 f5 10.Bd3 Nf6
11.OOO Bxc3 12.bxc3 Qe7 13.h3 Bd7,
Zinn  Handel, 1958
!.
 7...OO 8.OOO Bxc3 9.bxc3 exf3 10.gxf3 was analysed by
Genius 2. Here White's compensation, in addition to the bishop pair,
would be the open gfile, instead of the familiar ffile.
 7...Bxc3+ 8.bxc3 OO 9.Qc2 exf3 10.Nxf3 b6 11.Bd3 Bb7 12.OO
Re8 13.Ne5 a6 14.Rad1 Rb8 15.Bg5 h6 16.Bxf6 gxf6 17.Ng4 f5
18.Bxf5! exf5 19.Qxf5, 10 in 27,
Montenero  Kasparov Champion, 1996.
7.a3 Bxc3+ 8.bxc3
is what I used to play a lot for some time, or was driven to play, so
I started to call it the Modern Main Line.
The DDG used to be so exciting with no wellknown theory analysed
thoroughly up to move 25, but now we have variations up to move 15
that have been played several times  and are thus becoming "theory".
Discouraging...
Black has also tried other moves after 7.a3:
 7...Ba5!? 8.Be3 exf3 9.Nxf3 Ne4 10.Qb3 OO 11.Be2 Bxc3+
12.bxc3 Na5 13.Qc2 Nd6 14.c5 Nf5 15.Bf4 b6 16.cxb6 axb6 17.OO
Nc6 18.Bd3 Nce7 19.g4 Nd5 20.Bg5 f6 21.gxf5 fxg5 22.fxe6 Bxe6
23.Bxh7+, 10 in 36, Brause  Petrol, ICS 1997.
 7...Be7 8.Be3 OO 9.OOO exf3 10.gxf3 a5 11.Bd3 Bd7 12.Qc2
e5 13.d5 Nd4 14.Qf2 Nf5 15.Bd2 b6 16.Re1 Bd6 17.Kb1 Nd4 18.Be3
c5, 01 in 52, Brause  Milton, ICS 1997. With rating over 2700,
Milton is one of the strongest computers at ICS.
B


8...Bd7 looks like a tempoloss because White queen would go
to c2 anyway.
9.Qc2 OO 10.Bg5 e5 11.d5 Ne7 12.Bxf6 gxf6 13.fxe4 Ng6
14.g3, 10 in 25,
Heikkinen  Gum, Zone 1996.
9...exf3 10.Nxf3 OO 11.Bd3 Re8 12.OO (12.Ne5 Nxe5
13.dxe5 Ng4 14.Bf4)
e5 (12...b6? 13.Bg5 h6 14.Bxf6 gxf6 15.Nh4, 10 in 23,
Heikkinen  Chessmaster 3000, 1995)
13.Ng5! saves the day.
 13...g6 14.d5 Nb8 (14...e4!? 15.Rxf6 exd3 16.Qf2 Ne5 17.Rxf7
Rf8 18.Rxf8+ Qxf8 19.Qd4 +/)
 15.Qe2?!
(my fingerslip or actually mouseslip variation)
15...Nxd5??
(15...e4 16.Rxf6 Qxf6 17.Nxe4 unclear or 16...exd3 17.Qf1 Qe7?
18.Rxf7 Qe1 19.Rf8+ Kg7 20.Ne6+ Rxe6 21.Bh6+ Kxh6 22.Rxe1 +)
16.cxd5 e4 17.Bxe4 f5 18.Qe3 (or 18.d6 fxe4 19.Qc4+) fxe4 19.Nxh7
Kxh7 20.Qh6+ Kg8 21.Qxg6+ Kh8 22.Rf7 Qh4 23.Qg7# 10,
Heikkinen  phydeaux, Zone 1996.
 15.Qf2 was the move I intended to play.
 15.Nxf7 Kxf7 16.Bg5 +/.
 15.Rxf6?! Qxf6 16.Ne4 Qg7 17.Bg5 f5 unclear.
 13...h6 14.Bh7+ Kf8 15.Nxf7! Qe7 16.Nh8! +.
 13...e4? 14.Nxe4 Bg4 15.Nxf6+, 10 in 27,
Heikkinen  ryder, Zone 1996.
Alternatives after 11.Bd3:
 11...e5 12.OO e4!? is absolutely the best try.
 11...h6 12.OO Re8 13.Bf4 Nh5 14.Be3 e5 15.Bd2 Nf6 16.Rae1
Bg4 17.Nxe5 Nxe5 18.dxe5 Nd7 19.Bh7+ Kf8 20.Rxf7+ Kxf7 21.Qg6+
Kf8 22.Rf1+ Nf6 23.exf6 gxf6 24.Rxf6+ Ke7 25.Qf7# 10, Brause 
RankandFile, FICS 1996.
 11...Ne7 12.OO Qe8? 13.Bg5 Ng6 14.h4, 10 in 27,
Heikkinen  Rebel Decade, 1996
.
8...OO looks good for Black. This is one of the key lines
that needs more ideas for White: now White is desperately looking for
a tempo or two to be able to create immediate threats.
9.Qc2 exf3 10.Nxf3
 10...b6 11.Bd3 Bb7 12.OO Qd6? 13.a4 Rfd8 14.Ba3 Qd7 15.Rad1
h6 16.Ne5 Qe8 17.Rxf6 gxf6 18.Ng4 Kg7 19.Bc1, 10 in 40,
Heikkinen  Chessmaster 3000, 1994.
 10...e5! 11.dxe5 (11.d5 Ne7 12.Nxe5? Re8 /+; 11...e4 is also
good) Re8 12.Be2 Nxe5 13.Nxe5 Rxe5 14.OO Qe7 15.Bd3 Qc5+ 16.Qf2
Qxf2+ 17.Rxf2 Re1+ 18.Rf1 Rxf1+ 19.Kxf1 Be6 20.Bf4, draw in 57,
Laucius  Genius 2, 1996.
 10...Re8
 11.Ne5?! Nxe5 12.dxe5 Nd7 13.Qe4 Nc5 14.Qe3 Nb3 /+,
Heikkinen  Ramakers, Zone 1996.
 11.Bf4 Nh5 12.Bg5 Qd6
(12...f6 13.Bd3 fxg5 14.Bxh7+ Kf8 15.Bg6 Nf4 16.OO e5 17.Bxe8
Qxe8 18.Qh7 Qe7 19.Rae1 Be6 20.Nxe5 10,
Laucius  GNU WebChess, 1996)
13.Bd3 e5 14.Bxh7+ Kh8 15.d5 g6 16.Bxg6 Qxg6 17.Qxg6 fxg6
18.dxc6 e4 19.Nh4 bxc6 20.Nxg6+ 10,
Laucius  Boni, Internet 1996.
 11.Bg5 e5 12.d5 e4 /+.
 10...h6 transposes to the Lalic game below.
9.Bg5 h6 10.Bh4
 10...Nb8! 11.Qc2 e3 12.f4? c5 13.Nf3 Nc6 14.Ne5 cxd4, 01 in
32,
Heikkinen  Mayers, 1996
!.
White often rolls over Black who plays useless waiting moves. In this
game, however, Black had admirable insight into the DDG, by playing
the antidote c5 straight away.
 10...exf3 11.Nxf3 e5 12.OOO e4 13.Ne5 Ne7 14.Be2 Nf5 15.Bf2 Nd7
16.g4 Qg5+ 17.Kb1 Nxe5 18.dxe5 e3 19.Be1 Ne7 20.Bg3 Bxg4 21.Bxg4 Qxg4
22.Qd7 Nf5 23.Rhg1 e2 24.Rde1 Rfd8 25.Qxc7 Qe4+ 26.Ka1 Qc2 01,
Heikkinen  Walkenhorst,
corr. 19961997.
9.Bf4? e5 10.dxe5 (10.Bxe5 Nxe5 11.dxe5 Re8 12.exf6? exf3+
wins) Nh5 11.Rd1 Qe7 12.Bg3 Nxg3 13.hxg3 Qxe5 14.Ne2 exf3 15.gxf3 Re8
16.Kf2 Qe3+ 17.Kg2 Bf5 01, Jorgensen  Heikkinen, corr. 1999.
8...h6 is based on a simple but effective idea: prevent
White's bishop from coming to g5, creating an annoying pin. White
could then try to attack the h6pawn with timely Bf4 and Qd2, so Black
must keep him busy.
9.Qc2 exf3 10.Nxf3 OO 11.Be2 e5 12.dxe5 (12.d5!?) Ng4
13.Bf4 Qe7
 14.OO Qc5+ (14...Ngxe5 15.Nxe5 Nxe5 16.Qe4 =/+) 15.Kh1 Nf2+
16.Rxf2 Qxf2 17.Qe4 (17.Rf1 Qc5 18.Qe4 looks promising) Bf5
18.Qxf5 Qxe2 19.Bxh6! gxh6? 20.Ng5! hxg5 21.Qxg5+ draw with
perpetual check,
Heikkinen  GM Lalic, 1996
.
 14.Qe4!? Re8 (14...f5 15.Qd5+ Be6 16.Qb5 g5 unclear, or
15...Qe6? 16.h3) 15.Bd3 f5 (15...g6! looks good) 16.Qd5+ Qe6
17.Qxe6+ Rxe6 18.Nd4 Ngxe5 (18...Re8! 19.Nxc6 bxc6 =/+) 19.Nxe6
Nxd3+ 20.Kd2 unclear.
11.Bd3
 11...e5 12.dxe5 Re8 13.OO Nxe5 14.Nxe5 Rxe5 15.Bf4 Re8
16.Bg3 Qe7 17.Bh4 Qc5+ 18.Bf2 (18.Kh1 Ng4 19.Bh7+ Kh8 /+;
19...Kf8?? 20.Rxf7+! +) Qd6 19.c5 Qd5 20.Bd4 Ng4 21.h3 Ne5
22.Rae1 f6 23.Be4 Qd8 24.Qb3+, draw in 47,
Laucius  Genius 2, 1996.
 11...b6 12.OO Bb7 13.Qe2 Re8 14.Ne5 Nxd4 15.cxd4 Qxd4+
16.Kh1 Qxa1 17.Bb2 Qa2 18.Rxf6 gxf6 19.Qh5 Re7 20.Qxh6 f5 21.Nc6
10,
Etxeberria  Amondarain, 1997.
Looks like this is almost instantly winning for Black:
6.Qb3?! c5 7.Bf4 (7.Be3 and 7.dxc5 are hardly better) Bxc3+
(7...cxd4 8.Qxb4 dxc3 9.Qxc3 /+; but not 7...Qxd4?? 8.Rd1 +)
8.bxc3 cxd4 9.Rd1 /+.
Again, in practice, Black has played worse: 6...Nc6 7.Be3
 7...OO 8.OOO Bxc3 9.Qxc3 Qe7
 10.a3 a6 11.Qc2 Bd7 12.fxe4 Rfb8 13.Nf3 b5 14.Ng5 (14.e5!) h6
15.h4 e5, Markwardt  Schulz, 1956.
 10.Nh3 Rd8 11.Bg5 h6 12.Bh4 g5 13.Bf2 Qb4 14.Qc2 e5 15.d5 Nd4
16.Bxd4 exd4 17.fxe4 Re8 18.Nf2, 10 in 34, Heikkinen  Rantanen,
2002.
 7...e5 8.a3 (8.d5 +/=) Bd6 9.d5 Nd4 10.Bxd4 exd4 11.Nxe4 Nxe4
12.fxe4 Qh4+ 13.Kd2 Qxe4 14.Re1? Bf4+ 15.Kd1 Be3 16.Nf3 Bg4
17.Be2 Qb1# 01,
Heikkinen  Pietilä, 1996.
 7...exf3 8.Nxf3 (8.gxf3!?) Ne4 9.d5 exd5 10.cxd5 Qe7! 11.dxc6 Nxc3
12.Kf2 Ne4+ 13.Kg1 Nc5 01 (14.Bb5 is not enough), Heikkinen 
Jorgensen, corr. 2000, is my most embarrassing loss.
Outside the two main lines, there are hardly better moves for White.
 6.fxe4 Nxe4 7.Qd3 Nxc3 (7...f5 is strong) 8.bxc3 Bd6 or
8...Ba5 intending c5 are good for Black.
 6.Bg5 c5 (6...Nc6 is also awkward enough) 7.dxc5 Bxc3+ 8.bxc3
Qxd1+ 9.Rxd1 Nbd7 10.c6 bxc6 /+ analysed Genius 2.
 6.Be3 Nc6 would transpose, but there
must be something better for Black.