Chess Openings Lab
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Sicilian Defense: O'Kelly Variation

The O'Kelly Variation is 2...a6, a waiting move that takes b5 away from White's pieces before Black picks a setup. Black hopes White plays d4 into a prepared ...cxd4 and ...e5, while White wants a setup where ...a6 is wasted, such as c4 or c3.

Moves
1.e4 c5 2.Nf3 a6
ECO
B28
Engine
+0.45 · a slight edge for White (Stockfish 17.1, depth 20)
Played
5,598 games in our lichess sample
White scores
51.5%

Key ideas for both sides

White

  • Play 3.c4, the top engine move, and build the Maroczy bind with Nc3 and d4 so that ...a6 does little.
  • The quiet 3.c3 prepares d4 with a full pawn center; if Black hits with ...d5, take on d5 and play d4.
  • A kingside fianchetto with g3 and Bg2, followed by e5, gains space and makes ...a6 look slow.
  • If you choose d4, know the ...cxd4 and ...e5 ideas, because the knight has no b5 square.

Black

  • Against 3.c4, play ...e6, ...Qc7 and ...Nf6, a Kan-style setup where ...a6 already fits.
  • Against 3.c3, strike with ...d5 and recapture with the queen, since the c3 pawn takes the knight's best square.
  • Against the g3 line, develop ...Nc6 and ...Nf6, and if e5 comes, use ...Ng4 and ...c4 against the pawns.
  • Keep ...b5 in mind: the a6 pawn supports it and gains queenside space.

Plans and pawn structure

The O'Kelly is a move-order fight. Black spends a tempo on ...a6 to keep b5 free of white pieces and to prepare ...b5. If White answers with c4, a Maroczy bind arises after d4, and Black must play slowly with ...e6, ...Qc7 and ...Nf6, hoping to use the a6 pawn for ...b5 later. If White plays c3, Black frees the game with ...d5. In every case White tries to make ...a6 a lost tempo.

Where the engine's main line heads: Maroczy bind: White pawns on c4 and e4. The Maroczy bind: White pawns on c4 and e4 clamp the d5 square, so Black's ...d5 and ...b5 breaks are hard to play.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position +0.45: a slight edge for White. Its three top choices for White:

  1. +0.45 3.c4 e6 4.Nc3 Qc7 5.d4 cxd4
  2. +0.43 3.g3 Nc6 4.Bg2 Nf6 5.e5 Ng4
  3. +0.38 3.c3 d5 4.exd5 Qxd5 5.d4 Nf6

Pawns, from White's side.

How it scores on lichess

5,598 rated lichess games reached this position; White scored 51.5%.

under 120048.2%
1200–159952.5%
1600–199950.9%
2000 and up52.3%

Light: White wins. Grey: draws. Dark: Black wins. About the sample.

Where it goes next

How to play against it

As White, do not rush into d4 without knowing the ...cxd4 and ...e5 ideas. 3.c4 or 3.c3 are the most reliable answers, because the a6 pawn does little against those pawn structures. Develop normally, take space, and Black's extra queenside move is just slow.

Questions

What are the moves of the Sicilian Defense: O'Kelly Variation?

The Sicilian Defense: O'Kelly Variation starts 1.e4 c5 2.Nf3 a6. Its ECO code is B28.

Is the Sicilian Defense: O'Kelly Variation good for Black?

Stockfish 17.1 rates the position +0.45 at depth 20, which is a slight edge for White. In 5,598 lichess games from our sample, White scored 51.5%. A tricky surprise weapon for Black players who know move orders well, but White players who choose c4 or c3 get a pleasant, simple game.

What is the main idea of the Sicilian Defense: O'Kelly Variation?

Black plays ...a6 before choosing a setup, taking b5 away from White's bishop and knights. The idea is to answer d4 with fast counterplay, so White often prefers c4 or c3 to make the extra move look slow.

What should White play next?

The engine's first choice is c4, with g3 and c3 close behind. 3.c4 sets up a Maroczy bind before Black can strike with ...d5, so ...a6 loses much of its point.

Updated October 2026. Sources and method.