Queen's Gambit Accepted: Classical Defense, Alekhine System

The Queen's Gambit Accepted: Classical Defense, Alekhine System is a chess opening classified under ECO code D28 in the Closed & Semi-Closed Games family, arising from 1.d4 d5, including the Queen's Gambit, Slav Defense, and related systems. It is reached after 7 moves: 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. e3 e6 5. Bxc4 c5 6. O-O a6 7. Qe2 b5. The resulting position leaves white to move.