O'Kelly Variation

The O'Kelly Variation spends Black's second move on another pawn advance rather than on development. The move ...a6 is a standard Sicilian resource, best known from the Najdorf, and here it comes before ...d6 or ...Nc6, so the line is sometimes described as an accelerated Najdorf. Its purpose is to take the b5-square away from both a white knight and a white bishop. That prepares an early ...e5 in the Open Sicilian without allowing Ndb5 or a disruptive Bb5+.

The most common reply, 3. d4, is the Normal System, and it is the one the variation is designed to meet. After 3...cxd4 4. Nxd4 Nf6 5. Nc3 e5 the attacked knight has no access to b5. Retreats such as 6. Nf3 or 6. Nb3 run into 6...Bb4, pinning the e4-defender, and ...d5 can follow. 6. Nf5 is met by 6...d5. The more careful retreat is 6. Nde2, so that after 6...Bb4 7. a3 a knight can recapture on c3 and keep e4 protected. White can also prefer 5. Bd3, guarding e4 with the bishop so that the pin loses its force. In online play Black scores slightly better than White after 3. d4.

White's alternatives aim to make ...a6 a lost tempo. 3. Nc3, the Yerevan System, covers e4 before opening the center. Black can enter a regular Najdorf with 3...d6 or stay in less explored territory with 3...b5 and pressure along the long light-squared diagonal. 3. c4, the Maróczy Bind, clamps d5 before the queen's knight comes out. Black can transpose to a Kan with 3...e6 or play independently with 3...Nc6 4. d4 cxd4 5. Nxd4 e5, though White keeps a space advantage either way. 3. c3, the Venice System, is an Alapin in which White has gained Nf3 for free. 3...d5 leads to an Alapin structure once White exchanges on d5. 3...e6 4. d4 d5 can become an Advance French after e5, with Black a move behind the usual lines. The engine's preferred replies are 3. c4 and 3. c3. Rarer tries include 3. Bc4, 3. d3, 3. g3, 3. Be2, 3. b3 and the Wing Gambit 3. b4.

The O'Kelly carries little theory and soon reaches unfamiliar positions, so it is used mainly as a surprise or in fast time controls. It is seldom seen at grandmaster level, where the theoretical verdict has long been unfavorable. The engine gives White a slight edge. Lichess results are almost even, although White does better after 3. c4 and 3. g3.