Chess Opening Theory/1. e4/1...Nf6/2. e5/2...Nd5/3. d4/3...d6/4. c4/4...Nb6/5. f4

= Alekhine's Defence - Four Pawns Attack =

White has built a huge pawn center. Black will try to destroy it from a distance. It would be a good idea to exchange the d pawn so as to weaken the king side : /5...dxe5/.

A more quiet line is : /5...Bf5/, developing the bishop. /5...g6/ is also a line which has been played by Magnus Carlsen - on g7 the bishop will exert pressure along the long diagonal, and helps to the attack against d4 and e5. It also gives White other attacking plans, such as h4-h5. 5...g5!? is an objectively unsound but creative idea, since 6.fxg5? dxe5 7.dxe5 Qxd1+ 8.Kxd1 Bg7 followed by ...Nc6 and ...Nd7 will win back the pawn with a much stronger structure & development, but declining it often allows White an advantage.

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