Chess puzzle (Advantage)
Opening: Sicilian_Defense, Sicilian_Defense_French_Variation
Moves: 1. e4 c5 2. Nf3 e6 3. b3 d6 4. Bb2 e5 5. c3 Nf6 6. Qc2 Be7 7. d4 Qc7 8. dxe5
dxe5 9. c4 Nc6 10. Nc3 O-O 11. Bd3 Rd8 12. O-O *
Position (FEN): r1br2k1/ppq1bppp/2n2n2/2p1p3/2P1P3/1PNB1N2/PBQ2PPP/R4RK1 b - - 6 12
Black to move.
Themes:  Middlegame  
Puzzle rating: 1624
Best move: Nb4