Chess Opening Theory/1. e4/1...c5/2. Nf3/2...d6/3. d4/3...cxd4/4. Nxd4/4...Nf6/5. Nc3/5...a6

Najdorf variation B90 Open Sicilian with ...d6 → 5. Nc3 6. Bg5 · main line 6. Be3 · English attack 6. Be2 · Opocensky variation 6. h3 · Adams attack 5...a6 · Najdorf variation Black plays 5...a6 and controls the b5 square. This is prophylaxis, removing White's options of Ndb5 or Bb5+, and supports further queenside expansion with ...b5 and ...b4 in the future, which could become dangerous for White should they castle queenside. Flexibility is a key to this opening: Black chooses to develop their knight to d7 or c6 in some lines; their bishops to b7 or e6 and e7 (if the e-pawn is advanced) or g7 (after ...g6) in different lines. 5...a6 prepares 6...e5, kicking the knight to b3, because the intermezzo 7. Bb5+ is prevented. However, it doesn't make any immediate threats, therefore White has a large variety of ways to continue: Develop a bishop 6. Bg5 is most popular: developing the dark squared bishop actively and threatening to double Black's pawns with an eventual Bxf6. As playing 6...e5 would leave the d5 square too weak, with White having far more control of it than Black, Black usually responds with 6...e6, entering a Scheveningen-type pawn structure. 6. Be3 is the English attack. White plans for a quick attack on the kingside: Qd2 and O-O-O, then a kingside pawn storm with f3, g4, and h4. This usually results in opposite-side castling, with a lot of dynamic play and chances for both sides. White can also develop the kings bishop: 6. Be2, the Opocensky variation, prepares to castle kingside. This is the calmer, positional move. If 6...e5, White exploits pressure on the weak d5 square. If Black plays 6...e6, White instead focuses on playing an eventual f4 and achieving a kingside attack. 6. Bc4 is the Lipnitsky attack. Usually Black responds with 6...e6, shutting down the bishop and increasing their control of the d5-square. White also usually castles kingside and Black usually fianchettoes the light squared bishop to b7. Occasionally the move 6. Bd3 is tried, though this is less common than 6. Be2 and 6. Bc4 as the bishop on d3 is obstructed by the pawn on e4, and the bishop on d3 blocks the queen's support of the d5-square. Attack on the kingside White can also try to accelerate his chances of a kingside attack by immediately pushing a kingside pawn. 6. f4 is the Amsterdam attack, in which White attacks the e5 square and creates a semi-open f-file to attack via. White also usually castles kingside in this line, and also often plays a4 soon after to prevent b5. 6. f3 may be called the anti-anti-English attack. After 6. Be3, the English attack,. Black has the option of 6...Ng4, the anti-English attack, which seeks to trade off the bishop. Playing 6. f3 first sidesteps this sideline and usually transposes to the back into the standard English attack after 6... e5 7. Nb3 Be6 8. Be3. 6. g3 is the Zagreb variation in which White fianchettoes the king's bishop to g2 in order to control the d5 square further, and discourage Black from playing ...b5, as that could make the g2-bishop quite powerful. 6. h3 is the Adams attack. In this variation, White controls the g4 square and prepares to play g4 for an eventual Kingside attack. If Black stops this with h5 in the future, White usually follows up with g3 and Bg2, and plays for the d5 square. 6. h4 has also been tried, where White aims to accelerate his queenside attack. This is less common than the other kingside pawn moves, as it's committal, and Black usually equalises. Lock up the queenside White can also try to slow down Black's attack on the queenside by pushing a queenside pawn: 6. a4 prevents ...b5 entirely, therefore shuts down Black's ability to expand on the queenside. 6. a3 allows ...b5 but prevents Black from playing ...b4 and kicking away the c3 knight in the future. Just like a4, it also weakens the queenside and if White castles queenside, this pawn could become a hook for Black's attack. In both these cases, due to the weakening of b4 and White's queenside, White usually must castle short and focus on controlling the d5 square, or play for an eventual f4. Miscellaneous moves 6. Rg1!?, the surprising Freak attack, aims to advance g4 eventually. This looks odd, but White intends to castle queenside and maintains flexibility with the kingside pawns, and can therefore decide the best places to advance them. 6. Nb3 anticipates that ...e5 will kick White's knight, and therefore removes the knight first. This discourages 6...e5 as a result, but also gives Black a tempo to play a move like 6...g6, getting an improved Dragon Sicilian. 6. e5?! is the Vleuten Gambit. This dubious sacrifice has the intention of quickly trying to undermine Black's structure. After 6...dxe5 7.Nb3 Qc7 White will try to quickly complete development while Black's play will involve defending the central pawn. History The Najdorf is named after the Polish-Argentinian Grandmaster Miguel Najdorf. It is the most popular variation of the entire Sicilian Defence. Theory table 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6 7 8 9 English Attack Be3e5 Nb3Be6 f3Nbd7 Qd2Be7 +/= Opocensky Variation Be2e5 Nb3Be7 O-OO-O Be3Be6 +/= Traditional Main Line Bg5e6 f4Qb6 Qd2Qxb2 Rb1Qa3 +/= Fischer-Sozin Attack Bc4e6 Bb3b5 O-OBe7 Qf3Qb6 = Amsterdam Attack f4e5 Nf3Nbd7 Bd3Be7 O-OQb6 +/= Delayed English Attack f3e5 Nb3Be6 Be3Be7 Qd2O-O +/= Adam's attackh3 e5Nde2 h5g3 Be6Bg2 b5 +/=Zagreb Variationg3 e5Nde2 Be7Bg2 O-OO-O b5 +/= Sicilian Defence, Najdorf Variation References fi:Shakkiaapinen/Peli/1. e4/1...c5/2. Rf3/2...d6/3. d4/3...cxd4/4. Rxd4/4...Rf6/5. Rc3/5...a6