Chess puzzle (Advantage)
Opening: Queens_Gambit_Declined, Queens_Gambit_Declined_Marshall_Defense
Moves: 1. d4 d5 2. c4 Nf6 3. cxd5 Nxd5 4. e4 Nb4 5. Qa4+ N8c6 6. d5 b5 7. Qb3 *
Position (FEN): r1bqkb1r/p1p1pppp/2n5/1p1P4/1n2P3/1Q6/PP3PPP/RNB1KBNR b KQkq - 1 7
Black to move.
Themes:  Opening  
Puzzle rating: 1417
Best move: Nd4