Classical Variation

The idea

White develops calmly with 5.Nf3 O-O 6.Be2, and Black strikes at the center with 6...e5. Now White has three main choices: 7.O-O, leading to the main line; 7.d5, closing the center at once; or 7.dxe5, exchanging into an endgame.

Plans for White

The most ambitious is 7.O-O, keeping the tension. After 7...Nc6 8.d5 Ne7 the center is closed, and White plays on the queenside. The quiet 7.dxe5 dxe5 8.Qxd8 Rxd8 leads to an early endgame where White hopes to use the d5 square.

Plans for Black

Against 7.O-O, the main move is 7...Nc6, provoking 8.d5 and the race of the Mar del Plata. Black can also choose 7...Na6 or 7...exd4 to keep the center more open.

Against 7.d5, play ...a5 to slow White's queenside expansion, then ...Nd7 or ...Na6 and ...f5.

Watch out for

For Black, the exchange endgame. After 7.dxe5 dxe5 8.Qxd8 Rxd8, watch for Bg5 and Nd5, which can hit the knight on f6 and the pawn on c7 together, the same idea that wins material in the Averbakh.

For White, closing the center at the wrong moment. Once d5 is played, Black gets a free hand on the kingside, so make sure the queenside play is ready.