Chess Openings Lab
a8b7c6d5e4f3g2h1

Sicilian Defense: O'Kelly Variation, Normal System

The Normal System of the O'Kelly is 3.d4, the direct central push against 2...a6. Black should take on d4 at once and use the a6 pawn to support ...e5 ideas, while White wants Nxd4 and fast development before Black's queenside setup pays off.

Moves
1.e4 c5 2.Nf3 a6 3.d4
ECO
B28
Engine
+0.15 · level (Stockfish 17.1, depth 20)
Played
1,916 games in our lichess sample
White scores
50.2%

Key ideas for both sides

White

  • After 3...cxd4, the engine prefers 4.Be2, a calm move that develops first and takes back on d4 next turn.
  • Once the knight lands on d4, watch for ...e5: with b5 covered by the a6 pawn, it usually drops back to b3.
  • If Black avoids the trade with ...e6, push d5, as the engine line shows, to gain space and cramp Black.
  • Against an early ...Qa5+, block with Bd2 and push d5 later; the queen has spent time for little.

Black

  • Take with 3...cxd4 right away. Delaying lets White push d5 or keep a big center with tempo.
  • Develop with ...Nc6 and ...Nf6, then hit the d4 knight with ...e5 when it cannot jump to b5.
  • Avoid 3...Qa5+ and 3...e6: both let White gain space with d5 and leave Black cramped.

Plans and pawn structure

After 3...cxd4 the position becomes an Open Sicilian where Black has already played ...a6. That move matters: the d4 knight has no b5 square, so ...e5 kicks it back to b3 or f3 without the usual Nb5 jump. Black then has the d5 hole and a backward d-pawn to manage, but quick development compensates. White aims for Nc3, Be3 and play against d5, possibly with Nd5 once the knights are out.

Where the engine's main line heads: Open Sicilian: White traded the d-pawn for Black's c-pawn. An Open Sicilian: White traded the d-pawn for Black's c-pawn. White has a lead in development and the d-file, Black has the half-open c-file and two central pawns.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position +0.15: level. Its three top choices for Black:

  1. +0.15 3...cxd4 4.Be2 Nc6 5.Nxd4 Nf6 6.Nc3
  2. +0.76 3...e6 4.d5 Nf6 5.Bd3 b5 6.b3
  3. +1.09 3...Qa5+ 4.Bd2 Qc7 5.d5 Nf6 6.Nc3

Pawns, from White's side.

How it scores on lichess

1,916 rated lichess games reached this position; White scored 50.2%.

under 120057.2%
1200–159954.4%
1600–199950.3%
2000 and up46.2%

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

Where it goes next

  • O'Kelly Variation, Normal System, Taimanov Line3...cxd4 · rare

How to play against it

As Black, answer 3.d4 with 3...cxd4 immediately. Then build with ...Nc6, ...Nf6 and ...e5, using the fact that the d4 knight cannot go to b5. Do not try 3...e6 or 3...Qa5+, which let White push d5 and keep a firm space edge.

Questions

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

The Sicilian Defense: O'Kelly Variation, Normal System starts 1.e4 c5 2.Nf3 a6 3.d4. Its ECO code is B28.

Is the Sicilian Defense: O'Kelly Variation, Normal System good for White?

Stockfish 17.1 rates the position +0.15 at depth 20, which is level. In 1,916 lichess games from our sample, White scored 50.2%. Fine for White players who like Open Sicilians, but Black is well prepared here, so White must play precisely to get anything.

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

White plays the natural d4 against the O'Kelly. Black's best is to trade with ...cxd4 and use the a6 pawn to make a later ...e5 stronger, since the white knight can no longer jump to b5.

What should Black play next?

The engine's first choice is cxd4, with e6 and Qa5+ close behind. 3...cxd4 trades the c-pawn for White's center pawn and opens the c-file before White can push d5.

Updated October 2026. Sources and method.