Chess puzzle (Advantage)
Opening: Ruy_Lopez, Ruy_Lopez_Berlin_Defense
Moves: 1. e4 e5 2. Nf3 Nc6 3. Bb5 d6 4. O-O Nf6 5. Nc3 a6 6. d4 *
Position (FEN): r1bqkb1r/1pp2ppp/p1np1n2/1B2p3/3PP3/2N2N2/PPP2PPP/R1BQ1RK1 b kq - 0 6
Black to move.
Themes:  Opening  
Puzzle rating: 1646
Best move: axb5