With 2.c4, White threatens to exchange a wing pawn (the c-pawn) for a centre pawn (Black's d-pawn) and dominate the centre with e2–e4. This is not a true gambit, as Black cannot hold the pawn, for example: 1.d4 d5 2.c4 dxc4 3.e3 b5? (Black tries to guard his pawn but should pursue development with 3...e5!) 4.a4 c6? 5.axb5 cxb5?? 6.Qf3! winning a piece.