Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...Nf6/4. O-O/4...Nxe4/5. d4/5...a6

Rosenthal variation Rio gambit accepted 5...a6 · Rosenthal variation Black now kicks White's bishop. Removing its pressure from Black's knight will allow Black to play ...d5, expanding in the centre and defending the knight on e4, without dropping a pawn due to the pin. Any retreat along the f1-a6 diagonal the bishop travelled on move 3 constitutes a loss of tempo and allows ...d5. The two serious possibilities are 6. Bxc6 or 6. Ba4. 6. Ba4 is a transposition to the Open Spanish. Reaching the Open Spanish via the Berlin defence is a move order trick that avoids sidelines like the Wormald attack. But White doesn't have to transpose into an Open Spanish if they do not want to: 6. Bxc6 dxc6 enters something like the Exchange variation, though there really is a threat of Nxe5 this time. Rather than recover the pawn straight away, White's better line is 7. Qe2, pressuring the e-file while unpinning the d-pawn to prevent a queen trade. Theory table 6. Bxc6 dxc6 7. Qe2 Bf5 8. Re1 Bd6 9. Qd3 O-O 10. Rxe4 Bxe4 11. Qxe4 f5 Rosenthal variation + 6. ... ... 7. ... ... 8. dxe5?! Bc5 9. Be3 Qe7 10. Bxc5 Nxc5 11. Nd4 Bg6 12. Nc3 O-O-O 6. Ba4 b5 7. Bb3 d5 8. dxe5 Be6 Open Spanish(by transposition) + References See also Ruy Lopez