Chess puzzle (Checkmate)
Moves: 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Bd2 c5 5. dxc5 Bxc5 6. h3 O-O 7. e3 d5 8. cxd5
Nxd5 9. Bc4 Nb6 10. Bb3 Bd7 11. Nf3 Bc6 12. Qe2 N8d7 13. O-O-O a5 14. Bc2 a4
15. a3 Qe7 16. e4 Bxa3 17. bxa3 Qxa3+ 18. Kb1 Qb4+ 19. Ka2 Nc4 20. Nb1 *
Position (FEN): r4rk1/1p1n1ppp/2b1p3/8/pqn1P3/5N1P/K1BBQPP1/1N1R3R b - - 5 20
Black to move.
Themes:  Middlegame Mate in 1 
Puzzle rating: 1081
Best move: Qb2#