Four Pawns Attack: the 5...dxe5 exchange

After 5.f4 Black exchanges on e5: White must choose between 6.fxe5, keeping the centre, and 6.dxe5, which allows the queen trade.

1.e4 Nf6 2.e5 Nd5 3.d4 d6 4.c4 Nb6 5.f4 dxe5

Move by move

1.e4 – White occupies the centre and opens diagonals for the queen and the f1-bishop.
1...Nf6 – The Alekhine Defence: the knight attacks e4 and invites the pawn forward, planning to attack the advanced white pawns later.
2.e5 – White accepts the challenge: the pawn chases the knight and gains space.
2...Nd5 – The knight centralises on d5, from where it eyes c3, b4, e3 and f4.
3.d4 – White adds a second pawn to the centre and supports e5.
3...d6 – Black immediately attacks the e5 spearhead: the typical way to challenge White’s centre.
4.c4 – The pawn chases the d5-knight and gains more space: White builds a big centre.
4...Nb6 – The knight retreats to b6, from where it presses on c4 and d5.
5.f4 – The Four Pawns Attack: White supports e5 with f4 and grabs maximum space, but the advanced pawns leave weak squares behind.
5...dxe5 – Black takes on e5 to open the d-file and make the d4-pawn a target.

White has four central pawns but lags in development; Black has opened the d-file against d4.

After 6.fxe5 Black plays ...Nc6 and ...Bf5 with pressure on d4, as in the main line of the chapter.
After 6.dxe5 Black trades queens with ...Qxd1+: White’s king loses castling and the c4, e5 and f4 pawns become targets in the ending.
Do not develop the bishop to g4 before White has played Nf3 or Be2: from d1 the white queen would capture it.

Against the Four Pawns Black does not wait: ...dxe5 opens the d-file and prepares the attack on d4.