Chess puzzle (Advantage)
Moves: 1. c4 e5 2. Nc3 Nc6 3. e4 d6 4. h3 Nf6 5. Nf3 h6 6. d3 Be7 7. Be2 O-O 8. O-O a6
9. a3 Na7 10. b4 b5 11. Bb2 bxc4 12. dxc4 Bb7 13. Nd5 Nxe4 14. Nxe7+ Qxe7 15.
Bd3 Nf6 16. Qc2 Nc6 17. Nh4 Nh5 18. Nf5 Qg5 19. g3 g6 20. Bc1 Nf4 21. Bxf4 *
Position (FEN): r4rk1/1bp2p2/p1np2pp/4pNq1/1PP2B2/P2B2PP/2Q2P2/R4RK1 b - - 0 21
Black to move.
Themes:  Middlegame  
Puzzle rating: 1360
Best move: exf4