Rather than 5.Bxf7+?, a better chance for White to play for is 5.Nxe4, even though 5...d5 regains the piece with a good game, e.g., 6.Bd3 (6.Bxd5? Qxd5 7.Nc3 Qd8 Estrin; 6.Bb5 dxe4 7.Nxe5 Qg5! Collijn's "Lärobok"; 6.d4 dxc4 7.d5 Ne7 8.Nc3 c6 Cordel–Schupli, 1905) 6...dxe4 (the recently discovered 6...Nb4 is also ) 7.Bxe4 Bd6 8.d4 Nxd4 9.Nxd4 exd4 10.Qxd4 0-0 11.Be3 (11.0-0 Bxh2+ wins) Qe7 (Tartakower–Atkins, London 1922) and now the natural 12.0-0 Be5 would be awkward for White. In the above line, more ambitious is 8...exd4 9.Nxd4 0-0!?, as in a match game between Siegbert Tarrasch and Emanuel Lasker in 1916, which led to a Black win in 23 moves.