Queen's Gambit Declined: Semi-Tarrasch Defense, San Sebastian Variation

The Queen's Gambit Declined: Semi-Tarrasch Defense, San Sebastian Variation is a chess opening classified under ECO code D41 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 9 moves: 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3 c5 7. Nf3 cxd4 8. cxd4 Bb4+ 9. Bd2 Qa5. The resulting position leaves white to move.