Queen's Gambit Declined - 4.Bg5 Nbd7
1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 Nbd7
White pushes the queen's pawn to d4. Black pushes the queen's pawn to d5. White plays the c-pawn to c4.
Black pushes the king's pawn to e6. White develops the knight to c3. Black develops the knight to f6.
White develops the dark-squared bishop to g5. Black transfers the knight to d7.