Ruy Lopez, Exchange Variation grandmaster play by Emanuel Lasker, and later invigorated with new ideas by Bobby Fischer. The Exchange Variation can be a powerful psychological weapon. Black is forced to play actively, which is psychologically difficult if all one needs is a draw. Lasker's famous win against Jose Raul Capablanca in the St. Petersburg 1914 chess tournament is an example of this. With a lead in the tournament, Capablanca was intent on simplifying the game to obtain a draw, but faced with the Exchange Ruy he played too passively and was routed by Lasker as a result. 4...dxc6 is the main recapture. Black's
Ruy Lopez, Exchange Variation than this. White now threatens 6.Nxe5 because the sequence 6...Qd4 7.Nf3 Qxe4 to regain the pawn, now fails to 8.Re1 pinning and winning the queen. "ECO" code C68 examines these responses to 5.0-0: 5...Qf6, 5...Qe7, 5...Bd6, 5...Qd6, or 5...Bg4 (all directly defending the e5-pawn, except 5...Bg4 which indirectly defends by pinning the knight). The moves 5...Be6, 5...Be7, and 5...Ne7 are less common moves which have never achieved popularity. The idea behind these moves is that if White plays to win a pawn with 6.Nxe5, 6...Qd4 7.Nf3 Qxe4 is again playable, as the Black minor piece on e6 or e7 blocks