Chess puzzle (Checkmate)
Opening: Blackmar-Diemer_Gambit_Declined, Blackmar-Diemer_Gambit_Declined_Elbert_Countergambit
Moves: 1. d4 d5 2. e4 dxe4 3. Nc3 Nf6 4. f3 e5 5. d5 c6 6. Nxe4 Qxd5 7. Nxf6+ gxf6 8.
Bd2 Bf5 9. c4 Qd4 10. Qb3 Bc5 11. O-O-O a5 12. Qxb7 Ba3 13. Bc3 *
Position (FEN): rn2k2r/1Q3p1p/2p2p2/p3pb2/2Pq4/b1B2P2/PP4PP/2KR1BNR b kq - 2 13
Black to move.
Themes: Pin, Queenside Attack Middlegame Mate in 1 
Puzzle rating: 1878
Best move: Qxc3#