Chess puzzle (Advantage)
Opening: St_George_Defense, St_George_Defense_Other_variations
Moves: 1. e4 a6 2. Nf3 Nc6 3. a4 e5 4. Bc4 Bb4 5. c3 Bc5 6. O-O d6 7. d3 Bg4 8. Qb3
Nh6 9. Qxb7 *
Position (FEN): r2qk2r/1Qp2ppp/p1np3n/2b1p3/P1B1P1b1/2PP1N2/1P3PPP/RNB2RK1 b kq - 0 9
Black to move.
Themes:  Middlegame  
Puzzle rating: 1615
Best move: Na5