Chess Opening Theory/1. d4/1...d5/2. c4/2...e6/3. Nc3/3...Nf6/4. Nf3/4...dxc4

4...dxc4 is a very aggressive response by Black leading to very double-edged positions. Black gives up some central control, allowing for White to build up a big center that Black tries to tear down later.

5. e4 is White's main response, taking up the entire center and preparing to recapture the pawn with the bishop.

5. e3 is the quiet variation. Positions often resemble those of the Queens Gambit accepted with 3. Nf3.

5. Qa4+ is a sideline with positions similar to the Semi Slav defence.

1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Nf3 dxc4