Najdorf Variation

The move 5...a6 makes no immediate threat but takes b5 away from White's knight and king's bishop. That matters because the direct 5...e5 can be met by 6. Bb5+ followed by Nf5, planting a knight that is hard to remove. With b5 covered, Black can later play ...e5 and push the d4-knight back without fearing a bishop check, and the a-pawn also supports a queenside expansion with ...b5 and ...b4 aimed at the c3-knight. Black keeps options open: the e-pawn can go to e5 or e6, the queen's knight to d7 or c6, and the light-squared bishop to b7 or e6.

The choice of e-pawn move sets the structure. After ...e5 Black gains central space but leaves a hole on d5 and a backward d-pawn, which White targets with pieces. After ...e6 a Scheveningen formation arises, with d5 more securely held. Opposite-side castling is common: White castles long and storms the kingside, while Black answers with ...b5, ...Bb7 and a knight heading for c4 via b6, using the half-open c-file.

White has an unusually wide range of sixth moves. 6. Bg5 is the most played, usually met by 6...e6 7. f4, after which 7...Be7 8. Qf3 Qc7 9. O-O-O Nbd7 forms the old main line and 7...Qb6 8. Qd2 Qxb2 9. Rb1 Qa3 is the very sharp Poisoned Pawn. 6. Be3, the English Attack, aims for f3, g4, Qd2 and queenside castling; it took its name from Nunn, Short and Chandler and is regarded as the modern main line. Some players start with 6. f3 to rule out the reply 6...Ng4. 6. Bc4, the Lipnitsky or Sozin Attack, eyes f7 and was a favorite of Fischer; Black usually blunts it with ...e6. 6. Be2, the Opocensky, leads to quieter positional play, and Karpov used it to exploit d5 after 6...e5. Less common tries include 6. h3 (the Adams Attack, preparing g4), 6. f4 (Amsterdam), 6. g3 (Zagreb) and 6. Rg1 (Petronić Attack).

The Najdorf is heavily theoretical and gives both sides winning chances. In the Lichess database White and Black score exactly the same, and the engine considers the starting position close to equal, preferring 6. h3, 6. f3 and 6. Be3. The line is named after Miguel Najdorf, who played it as early as 1937 and expanded its theory with fellow Argentine players during the 1950s. Fischer, Kasparov and Vachier-Lagrave are among the leading players who have relied on it.