Chess puzzle (Checkmate)
Opening: Queens_Gambit_Declined, Queens_Gambit_Declined_Marshall_Defense
Moves: 1. d4 d5 2. c4 Nf6 3. cxd5 Qxd5 4. Nc3 Qh5 5. Nf3 Bg4 6. Bf4 Na6 7. h3 O-O-O 8.
e3 Nc5 9. Bh2 Bxf3 10. gxf3 e6 11. Be2 Ncd7 12. Nb5 a6 13. Qc2 c6 *
Position (FEN): 2kr1b1r/1p1n1ppp/p1p1pn2/1N5q/3P4/4PP1P/PPQ1BP1B/R3K2R w KQ - 0 14
White to move.
Themes:  Middlegame Mate in 1 
Puzzle rating: 939
Best move: Na7#