Chess puzzle (Advantage)
Moves: 1. d4 c5 2. Nf3 cxd4 3. Nxd4 Nc6 4. e3 Nf6 5. c4 e5 6. Nb5 Bb4+ 7. N1c3 a6 8.
Nd6+ Kf8 9. a3 Bxd6 10. Qxd6+ Qe7 11. Qxe7+ Kxe7 12. e4 Nd4 13. Rb1 b6 14. Bd3
Bb7 15. f3 Bc6 16. O-O Rhb8 17. Bg5 h6 18. Bxf6+ gxf6 19. b4 b5 20. cxb5 Bxb5
21. Nxb5 *
Position (FEN): rr6/3pkp2/p4p1p/1N2p3/1P1nP3/P2B1P2/6PP/1R3RK1 b - - 0 21
Black to move.
Themes:  Middlegame  
Puzzle rating: 1322
Best move: axb5