Queen's Gambit Accepted: Old Variation, Korchnoi Gambit

The Queen's Gambit Accepted: Old Variation, Korchnoi Gambit is a chess opening classified under ECO code D20 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 6 moves: 1. d4 d5 2. c4 dxc4 3. e3 e5 4. Bxc4 exd4 5. Qb3 Qe7 6. Kf1. The resulting position leaves black to move.