Chessy
Alekhine Defense: O'Sullivan Gambit as Black
The O'Sullivan Gambit is sharp, but the numbers here are not kind to Black. After 1.e4 Nf6 2.e5 Nd5 3.d4 b5, White has a direct challenge to meet, and the engine already thinks the position is close to decided. That makes this a useful drill: you are not trying to show off a trap, you are trying to survive the opening and find the best continuation under pressure. Focus on the critical reply, the common mistakes, and the ideas that keep you in the game.
Play the Alekhine Defense: O'Sullivan Gambit against the engine
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Create a free account →The position is already dangerous for Black
Stockfish rates this +1.54, a near-winning advantage for White. That means you are in serious trouble and need to treat every move carefully. The good news is that this is exactly the kind of position a drill can help with: you can learn the key response instead of guessing over the board. In this line, Black is not looking for a dream attack; Black is looking for the most accurate practical defence.
What the engine wants you to do
The engine's best move here is Bxb5. The listed continuation is Bxb5 c5 c4 cxd4. That tells you the first priority is to meet White's challenge directly, not to drift into passive play. In a position like this, the opening principles matter even more than usual: stay active, respond to the threat, and do not waste time with slow moves when the position is already tense.
What the database says about this tabiya
Across 85,514 games at this exact position, White wins 43.0%, draws 2.7%, and Black wins 54.3%. Those results show that this is a very practical position for Black, even though the engine score is strongly against you. The most-played continuation is Bxb5 with 46,856 games, and it is also the engine's recommendation. Other popular tries include Nf3 with 18,327 games, c4 with 6,633 games, f4 with 4,392 games, c3 with 2,873 games, and Nc3 with 1,441 games.
The moves to watch for
Some replies are especially important to know because they are the ones that get tested most often. c4 is an inaccuracy and loses about 0.7 pawns; f4 is a mistake and loses about 1.0 pawns; Nc3 is an inaccuracy and loses about 0.7 pawns. In each case, the better move was Bxb5. If you are playing Black, this is a strong signal to meet White's most active tries with the engine move rather than allowing White to seize the initiative more cleanly.
Results across 85,514 Lichess games
| Most-played continuation | Games | White wins |
|---|---|---|
| Bxb5 | 46,856 | 41.0% |
| Nf3 | 18,327 | 41.3% |
| c4 | 6,633 | 56.1% |
| f4 | 4,392 | 40.3% |
| c3 | 2,873 | 46.0% |
| Nc3 | 1,441 | 50.4% |
Frequently asked questions
What opening is this after 1.e4 Nf6 2.e5 Nd5 3.d4 b5?
This is the Alekhine Defense: O'Sullivan Gambit. In the position after those moves, it is White to move and you are playing Black.
Is the O'Sullivan Gambit sound for Black?
In this exact position, the engine evaluation is +1.54, which is a near-winning advantage for White. The database results are more practical for Black, but the engine verdict is still very poor for Black.
What is the best move for Black here?
The engine's best move is **Bxb5**. The suggested continuation is **Bxb5 c5 c4 cxd4**.
Which White replies should I know most?
The most-played continuation is **Bxb5** with 46,856 games. Other common replies are **Nf3**, **c4**, **f4**, **c3**, and **Nc3**, and **c4**, **f4**, and **Nc3** are all marked as mistakes or inaccuracies.
How many games feature the Alekhine Defense: O'Sullivan Gambit?
Over 85K Lichess games have reached the Alekhine Defense: O'Sullivan Gambit position. White wins 43.0%, Black wins 54.3%, with 2.7% draws — based on real rated games.