Ruy Lopez 5.d4 exd4 6.Qxd4 and White is in . After 4...dxc6, the obvious 5.Nxe5 is weak, since 5...Qd4 6.Nf3 Qxe4+ 7.Qe2 Qxe2+ leaves White with no compensation for Black's bishop pair. There are two principal lines after 4.Bxc6 dxc6. In the late 19th and early 20th centuries, Lasker had great success with 5.d4 exd4 6.Qxd4 Qxd4 7.Nxd4. Since then, better defences for Black have been developed, and this line is considered to slightly favour Black. Jon Jacobs wrote in the July 2005 "Chess Life" (p. 21): "A database search (limited to games longer than 20 moves, both players FIDE 2300+) reveals
Salo Flohr players ever, and proved virtually invincible at the Olympiads of the 1930s. His tournament record was impressive, with his tactical skill and excellent endgame technique securing him many famous victories. FIDE awarded him the International Grandmaster title on its inaugural list in 1950. He made a number of important contributions to opening theory: a 'Flohr variation' can be found in no fewer than six major openings, including the Caro–Kann Defence, the Ruy Lopez, the English Opening, and the Grünfeld Defence. The Flohr–Zaitsev Variation of the Closed Ruy Lopez (1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5