Chess puzzle (Advantage)
Opening: Ruy_Lopez, Ruy_Lopez_Morphy_Defense
Moves: 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. d3 b5 6. Bb3 Bb7 7. c3 Be7 8. O-O
O-O 9. Nbd2 d5 10. a4 b4 11. exd5 Nxd5 12. Bxd5 Qxd5 13. Nc4 f5 14. Ne3 Qe6 15.
d4 exd4 16. cxd4 Rad8 17. d5 Qg6 18. Qb3 *
Position (FEN): 3r1rk1/1bp1b1pp/p1n3q1/3P1p2/Pp6/1Q2NN2/1P3PPP/R1B2RK1 b - - 2 18
Black to move.
Themes:  Middlegame  
Puzzle rating: 1759
Best move: Na5