Opening Open Defence

In the Open Defence, 3...a6 4.Ba4 Nf6 5.0-0 Nxe4, Black tries to make use of the time White will take to regain the pawn to gain a foothold in the centre. Play usually continues 6.d4 b5 (6...exd4, the Riga Variation, is considered inferior; the main line runs 7.Re1 d5 8.Nxd4 Bd6! 9.Nxc6 Bxh2+! 10.Kh1! (10.Kxh2 Qh4+ 11.Kg1 Qxf2+ draws by perpetual check.) Qh4 11.Rxe4+! dxe4 12.Qd8+! Qxd8 13.Nxd8+ Kxd8 14.Kxh2 Be6 (14...f5?? 15.Bg5#!) and now the endgame is considered to favor White after 15.Be3 or Nd2 (but not 15.Nc3 c5!, playing to trap the bishop)) 7.Bb3 d5 8.dxe5 Be6 and material balance is restored.

White has a variety of options at move 9, including 9.c3, 9.Qe2, and 9.Nbd2. The classical line starts with 9.c3 when Black can choose between 9...Nc5, 9...Be7, and the aggressive 9...Bc5. After 9.c3 Bc5 10.Nbd2 0-0 11.Bc2 Black must do something about the attack on the knight on e4. An old continuation is 11...f5, when after 12.Nb3 Ba7 13.Nfd4 Nxd4 14.Nxd4 Bxd4 White can gain some advantage with Bogoljubov's 15.Qxd4. Instead, the very sharp La Grande Variante continues 15.cxd4 f4 16.f3 Ng3 17.hxg3 fxg3 18.Qd3 Bf5 19.Qxf5 Rxf5 20.Bxf5 Qh4 21.Bh3 Qxd4+ 22.Kh1 Qxe5. Perhaps the most famous game in this variation is Smyslov–Reshevsky, 1945 USSR–USA Radio Match. An analysis of the line had just been published in a Russian chess magazine, and Smyslov was able to follow it to quickly obtain a winning position. Reshevsky had not seen the analysis and he struggled in vain to solve the position over the board with his chess clock running. The Dilworth Variation (or Attack), 11...Nxf2 12.Rxf2 f6 13.exf6 Bxf2+ 14.Kxf2 Qxf6 has scored well for Black. It leads to unbalanced endgames that are hard to play for both sides. Yusupov is one of the few grandmasters to often adopt the Dilworth.

In the Howell Attack, 9.Qe2, White aims for play on the d-file. Keres sometimes played this line.

Karpov's move, 9.Nbd2, limits Black's options. In the 1978 Karpov–Korchnoi World Chess Championship match, following 9.Nbd2 Nc5 10.c3 d4 (10...Be7 is an old move that remains popular) Karpov introduced the surprising 11.Ng5!?, a move suggested by his trainer, Igor Zaitsev. If Black takes the knight with 11...Qxg5 White regains the material with 12.Qf3. This variation played a decisive role in a later World Championship match, Kasparov–Anand 1995, when Anand was unable to successfully defend as Black.

Open Defence after 8...Be6