Consider Rubinstein's instructive victory over Georg Salwe in 1908.
Rubinstein,Akiba - Salwe,Georg [D33]
1.d4 d5 2.Nf3 c5 3.c4 e6 4.cxd5 exd5 5.Nc3 Nf6 6.g3 Nc6 7.Bg2 cxd4 8.Nxd4 Qb6 9.Nxc6 bxc6 10.0–0 Be7
White to move
11.Na4 Qb5 12.Be3 0–0 13.Rc1 Bg4 14.f3 Be6 15.Bc5 Rfe8 16.Rf2 Nd7 17.Bxe7 Rxe7 18.Qd4 Ree8 19.Bf1 Rec8 20.e3 Qb7 21.Nc5 Nxc5 22.Rxc5 Rc7 23.Rfc2 Qb6 24.b4 a6 25.Ra5 Rb8 26.a3 Ra7 27.Rxc6 Qxc6 28.Qxa7 Ra8 29.Qc5 Qb7 30.Kf2 h5 31.Be2 g6 32.Qd6 Qc8 33.Rc5 Qb7 34.h4 a5 35.Rc7 Qb8 36.b5 a4 37.b6 Ra5 38.b7 1–0
The diagram position has been reached 66 times in the ChessBase Online Database. Five different moves have been tried by White, and all have a positive score. Rubinstein's 11.Na4 is the second most popular move. More popular is 11.e4, first played by Frank Marshall in 1912.
Isaak Boleslavsky demonstrated a winning plan with 11.e4 in 1953.
Boleslavsky,Isaak - Stoltz,Goesta [D33]
1.d4 d5 2.c4 e6 3.Nc3 c5 4.cxd5 exd5 5.Nf3 Nc6 6.g3 cxd4 7.Nxd4 Qb6 8.Nxc6 bxc6 9.Bg2 Nf6 10.0–0 Be7 11.e4 dxe4 12.Be3 Qxb2 13.Nxe4 0–0 14.Bd4 Qa3 15.Bxf6 Bxf6 16.Nxf6+ gxf6 17.Qh5 Kg7 18.Rae1 Rb8 19.Bxc6 h6 20.Re4 f5 21.Rh4 Qd6 22.Qf3 Rb6 23.Bd5 Rd8 24.Qc3+ Qf6 25.Qxf6+ Rxf6 26.Bb3 f4 27.Rxf4 Rxf4 28.gxf4 Kf6 29.Rc1 Rg8+ 30.Kf1 Ba6+ 31.Ke1 Re8+ 32.Kd2 Rd8+ 33.Ke3 Re8+ 34.Kd4 Rd8+ 35.Ke3 Re8+ 36.Kd4 Rd8+ 37.Kc3 Rd7 38.Kb4 Bb7 39.Rc5 Bf3 40.Kc3 h5 41.h4 Re7 42.Kd4 Re1 43.Rc7 Re7 44.Rc5 Re1 45.Ra5 Re4+ 46.Kd3 Re7 47.Kc3 Re2 48.Rxa7 Kf5 49.Rxf7+ Kg4 50.f5 Rxf2 51.f6 1–0
Which move is superior? Rubinstein's game was called a perfect model game shortly after it was played, and yet Boleslavsky opted to follow Marshall's idea, which has become more popular. Are both lines equally correct?