Najdorf Variation, Amsterdam Variation

The Amsterdam Variation, 6. f4 (ECO B93), is one of White's less common answers to the Najdorf. The pawn advance contests the e5 square and prepares to use the f-file against Black's kingside. Unlike in the English Attack, White usually castles short here, and a4 often follows soon to stop Black's ...b5 expansion.

Black's two main replies are about equally popular. 6...e5 hits the d4-knight and confronts the f4-pawn. After 7. Nf3 Nbd7 8. a4 Be7 9. Bd3 O-O, the knight has gone to f3 rather than b3. 6...e6 keeps a Scheveningen structure, with 7. Be2 a natural reply, and 6...Qc7 7. Bd3 is another option. Daniel King has advocated 6...g6, a sturdier kingside formation that aims for ...Qb6 on the g1–a7 diagonal to hinder White's short castling. One example is 7. Nf3 Bg7 8. a4 Nc6 9. Bd3 Qb6, where the knight goes to c6 rather than d7. In the Lichess database this fianchetto scores well for Black, and the engine rates the position after 6. f4 as balanced.