Chess Opening Theory/1. d4/1...d5/2. c4/2...dxc4/3. Nc3

Queen's Gambit Accepted
a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h
Position in Forsyth-Edwards Notation (FEN) rnbqkbnr/ppp1pppp/8/8/2pP4/2N5/PP2PPPP/R1BQKBNR b
Moves: 1. d4 d5 2. c4 dxc4 3. Nc3

3. Nc3

Two players have labeled this move misguided, as the knight is vulnerable here to a b7-b5-b4 advance. It also doesn't control d4 or e5, two important squares in Queen's Gambit Accepted positions. The most common and highest-scoring response for Black is to follow up with 3...a6, preparing a future ...b5 thrust which will introduce the idea of attacking the knight with ...b4, whilst also claiming that Black can keep ahold of the pawn with suitable defence. This usually leads to a firefight on the queenside, with a4 usually being played sooner rather than later by White in order to disrupt Black's defence of the c-pawn. The less common 3...c6 transposes to a position in the Slav defence, with a similar idea in mind.

Theory table

3	4	5	6
Nc3 c6	e3 b5	a4 b4	Ne4 Qd5	=
... ...	e4 b5	a4 b4	Nb1 Ba6	=
... a6	a4 Nc6	Nf3 Nf6	e4 Bg4	=/+
... ...	... ...	... Bg4	e3 Na5	=/+
... ...	... ...	... e5	Nxe5 Nxe5	=/+
... ...	e3 b5	a4 b4	Bxc4 e6	=