Chess puzzle (Advantage)
Opening: Ruy_Lopez, Ruy_Lopez_Berlin_Defense
Moves: 1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O Nxe4 5. Re1 Nd6 6. Bxc6 dxc6 7. Nxe5 Be7
8. Qe2 O-O 9. Nxc6 bxc6 10. Qxe7 Qxe7 11. Rxe7 Nb5 12. a4 Nd4 13. c3 *
Position (FEN): r1b2rk1/p1p1Rppp/2p5/8/P2n4/2P5/1P1P1PPP/RNB3K1 b - - 0 13
Black to move.
Themes:  Middlegame  
Puzzle rating: 1924
Best move: Nb3