Chess Opening Theory/1. e4/1...c5/2. Nf3/2...d6/3. d4

White plays 3. d4, inviting Black to trade a pawn and open the position.

3...cxd4 is the main move. Black captures towards the centre with a flank pawn, breaking up White's two pawn centre. Once White recaptures 4. Nxd4, Black has two central pawns to White's one, and a semi-open c-file to use. White meanwhile has opened attacking lines: both bishops have access to the game, and their queen has the semi-open d-file.

The game usually continues 4...Nf6 (attacking e4) 5. Nc3, and from there, Black can choose their flavour of ...d6 Sicilian, including the Najdorf (5...a6), classical (5...Nc6), or dragon (5...g6) Sicilians.

3...Nf6 is a minor sideline. 3...Nf6 attacks e4, and after 4. Nc3 to defend it, play usually transposes to the main line after 4...cxd4 5. Nxd4. By compelling Nc3, this move order prevents White from playing c4, a useful move that gains space and increases White's control over the d5 square (a pawn structure known as the Maróczy bind).

This lets Black move-order White around the Prins variation, a sideline after 3...cxd4 4. Nxd4 Nf6 where White plays 5. f3 to defend e4, so they may play c4 before they play Nc3. On the other hand, 3...Nf6 comes with the disadvantage of allowing 4. dxc5.

1. e4 c5 2. Nf3 d6 3. d4

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