Chess Opening Theory/1. e4/1...c6/2. d3/2...d5

Black plays 2...d5, supported by the pawn on c6. The main choice White faces is whether to allow a queen trade or not.

When White played 2. d3, they prepared to allow Black to take on e4 and recapture it with the d-pawn, but presently the d-pawn becomes pinned to White's queen. If White allows this, e.g. 3. Nf3, then after 3...dxe4 4. dxe4 the queens see each other, and 4...Qxd1+ 5. Kxd1 for an even endgame.

After 3. Nf3 dxe4, White still has an opportunity to avoid the endgame by gambitting a pawn: 4. Ng5!? exd3 5. Bxd3 is a sharp line that affords White some practical success.

If White wishes to avoid the queen trade, they may play 3. Nd2 to prevent the d-pawn becoming pinned to the queen. After 3...dxe4 White can actually capture either way, 4. dxe4 or 4. Nxe4, though the former is more common.

Usually Black leaves the tension with 3...e5 and the game continues resembling a King's Indian Attack, where White plays Nf3, g3, Bg7 and O-O. This is the mainline Breyer variation.

3. exd5?! would be strange: when White played 2. d3, they prepared to allow Black to take on e4 and recapture with the d-pawn if they did. After 3. exd5?! cxd5 White will eventually want to play d4 and so has lost a tempo compared to playing 2. d4.

3. Nc3 is interesting: after 3...dxe4 White can retake with the knight instead and avoid the queen trade that way. 3...d4 kicks the knight and Black can take more space in the centre, but is playable for White.

For explanation of theory tables, see theory table and for notation, see algebraic notation.

1. e4 c6 2. d3 d5

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• Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.

• Modern Chess Openings: MCO-14. 1999. Nick de Firmian, Walter Korn. ISBN 0-8129-3084-3.

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.