Four Pawns Attack

The Four Pawns Attack, 5. f4, sets up pawns on c4, d4, e5 and f4. This front is broad but not fixed, and pushing it further is double-edged: c5 gives a black knight d5, while d5 loosens e5. White therefore has to consolidate before Black's pieces and breaks take effect. Black aims mainly at d4, though c4 can also come under fire from ...Na5. The usual reply is 5...dxe5 6. fxe5 Nc6, attacking d4. White normally continues 7. Be3, because 7. Nf3 Bg4 puts heavy pressure on d4. One answer to that pin is 8. e6 fxe6 9. c5, the Ilyin-Zhenevsky Variation. After 7. Be3 Bf5 8. Nc3 e6 9. Nf3, Black chooses between 9...Be7, preparing ...f6, and 9...Qd7 with queenside castling, the Tartakower Variation.

Black has three other fifth moves. The Fianchetto Variation, 5...g6, has been played by Magnus Carlsen; the bishop bears on d4 and e5, though White gains ideas such as h4-h5. The Trifunovic Variation, 5...Bf5, is quieter. The Cambridge Gambit, 5...g5, also called the Planinc Variation after Albin Planinc, is objectively unsound, but 6. fxg5 dxe5 favors Black. Engines give White a slight edge, yet Black scores better in online games. The line is not especially popular, since many White players avoid sharp lines that Black may have prepared.