Chess puzzle (Crushing)
Opening: Queens_Gambit_Declined, Queens_Gambit_Declined_Exchange_Variation
Moves: 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. cxd5 exd5 5. Bf4 c6 6. e3 Qb6 7. Qc2 g6 8. Bd3
Bg7 9. Nf3 O-O 10. h3 Na6 11. a3 Nc7 *
Position (FEN): r1b2rk1/ppn2pbp/1qp2np1/3p4/3P1B2/P1NBPN1P/1PQ2PP1/R3K2R w KQ - 1 12
White to move.
Themes:  Middlegame  
Puzzle rating: 1627
Best move: Na4