Ruy Lopez, Exchange Variation Qf6 7.Qd3. There are two "ECO" classifications for the Exchange Variation. Bibliography Ruy Lopez, Exchange Variation The Exchange Variation of the Ruy Lopez is a chess opening that begins with the moves: Black may recapture on c6 with either pawn; although 4...bxc6 is playable, 4...dxc6 is almost always chosen at master level. Black has gained the at the cost of a weakened pawn structure, due to his doubled pawns on c6 and c7. White aims to reach an endgame in which he has the superior pawn structure, which may become an important factor. Thus, Black is compelled to strive for
Ruy Lopez play 8.c3, Black can and often does play 8...d6, which is just the main line in another order. But he can also play 8...d5 for the Marshall Attack. One of Black's more aggressive alternatives is the Marshall Attack: after 3...a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5 7.Bb3 0-0 8.c3 Black plays the gambit 8...d5, sacrificing a pawn. The main line begins with 9.exd5 Nxd5 (9...e4?!, the Herman Steiner variation, is considered weaker) 10.Nxe5 Nxe5 11.Rxe5 c6 (Marshall's original moves, 11...Nf6, and 11...Bb7 are considered inferior, but have also yielded good results at top levels of play for Black. GM Joel