Chess puzzle (Advantage)
Opening: Zukertort_Opening, Zukertort_Opening_Black_Mustang_Defense
Moves: 1. Nf3 Nc6 2. c4 e5 3. d3 Bc5 4. Nc3 Nf6 5. g3 O-O 6. a3 b6 7. Bg2 d6 8. Nd2
Bb7 9. b4 Bd4 10. b5 *
Position (FEN): r2q1rk1/pbp2ppp/1pnp1n2/1P2p3/2Pb4/P1NP2P1/3NPPBP/R1BQK2R b KQ - 0 10
Black to move.
Themes:  Middlegame  
Puzzle rating: 2324
Best move: Na5