Chess puzzle (Advantage)
Moves: 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 O-O 8. c3
d5 9. exd5 Nxd5 10. Nxe5 Nxe5 11. Rxe5 c6 12. d4 Bd6 13. Re1 Qh4 14. g3 Qh3 15.
Qe2 Bg4 16. Qf1 Qh5 17. Nd2 f5 18. f3 Bh3 19. Qf2 Kh8 20. c4 *
Position (FEN): r4r1k/6pp/p1pb4/1p1n1p1q/2PP4/1B3PPb/PP1N1Q1P/R1B1R1K1 b - - 0 20
Black to move.
Themes:  Middlegame  
Puzzle rating: 2013
Best move: Nb4