Chessy
The London System: Facing 3...c5
You've played 1.d4 d5 2.Nf3 Nf6 3.Bf4, and now Black pushes c5 — the most popular and principled challenge to the London System. After 4.e3, you've reached a position that has been played nearly 750,000 times on Lichess alone. Stockfish evaluates this dead level at +0.12, meaning neither side enjoys an advantage from the opening. That makes this a hard-fought fight for the centre where small decisions matter. Below the interactive drill you'll find the statistics, the engine's recommendation, and the mistakes to avoid — everything you need to feel confident playing this position as White.
Play the London System: c5 against the engine
Free, no signup — you play white, the engine adapts to your level.
Play the position yourself in the interactive drill below — test your plan against the engine and see if you can improve on the 47.7% White win rate.
Create a free account →What You're Fighting For: The Centre
After 4.e3, the central pawns on d4 and e3 face Black's pawn on d5 and the pressure from ...c5. Your main goal is to complete development smoothly. The engine's preferred continuation is 4...Nc6 5.Nbd2 cxd4 6.exd4, which leaves White with a pawn on d4 and Black with a pawn on d5 — a symmetrical-looking centre but with the bishop on f4 already outside the pawn chain. That bishop is a key asset: it pins Black's knight if it ever lands on e4, and it keeps an eye on the queenside. You'll want to follow up with moves like c3, Bd3, 0-0, and then decide whether to play for the minority attack on the queenside or build pressure in the centre with Re1.
What the Numbers Say About Your Chances
In the 747,397 games reaching this position, White wins 47.7% of the time, Black wins 48.3%, and draws occur in 4.0% of games. Those numbers tell an honest story: the opening is razor-sharp in practice despite the engine calling it dead level. Black's slight edge in winning percentage is likely tied to the practical difficulty of playing London positions accurately. But here's the encouraging side: when Black plays the most popular move, Nc6, White's winning percentage actually drops to 46.3%. By contrast, against 4...e6 you score a solid 50.4%, and against 4...Bg4 you score 49.4%. The worst reply for White to face is 4...Qb6, which gives you only 45.5% — so be alert for that queen sortie.
The Engine's Best Move and How to React
Stockfish rates 4...Nc6 as the strongest reply, and it is by far the most common, appearing in 387,604 games. The recommended line continues 5.Nbd2 cxd4 6.exd4. After that, the position is symmetrical and quiet, but you have two useful plans. You can play c3 to support the d4-pawn and then develop the light-squared bishop to d3, or you can play Bd3 immediately and castle kingside. The key is to avoid moving the f4-bishop again unless provoked — it is already well placed. If Black tries to trade dark-squared bishops with ...Bd6, you can recapture with the queen or consider playing Bg5, depending on the specific position.
The One Mistake Many Players Make
According to the database, 4...Bf5 is played about 31,325 times and is an inaccuracy that loses roughly 0.9 pawns in evaluation. The engine says that move is a mistake; Black should have played Nc6 instead. If your opponent plays 4...Bf5, you can be happy. Your best reply is probably 5.c4, challenging the centre immediately, or 5.Nc3 pressuring the d5-pawn. The bishop on f5 becomes a target after you play Bd3 and trade it off, leaving Black with a weaker light-squared bishop and you with the bishop pair. Watch for 4...Bf5 — it's a gift you can punish.
Results across 747,397 Lichess games
| Most-played continuation | Games | White wins |
|---|---|---|
| Nc6 | 387,604 | 46.3% |
| e6 | 112,578 | 50.4% |
| cxd4 | 73,951 | 48.9% |
| Qb6 | 63,361 | 45.5% |
| Bg4 | 42,472 | 49.4% |
| Bf5 | 31,325 | 49.9% |
Frequently asked questions
Is the London System good against 1...d5?
Yes, the London System (1.d4 d5 2.Nf3 Nf6 3.Bf4) is a solid opening that avoids heavy theory. The c5 reply is Black's most popular way to fight for equality, and after 4.e3 the position is dead level according to Stockfish (+0.12). White wins roughly 47.7% of games from this point, so the opening is perfectly playable at any level.
What is the most common mistake in the London System: c5?
The most notable mistake from the database is 4...Bf5, which is an inaccuracy that costs Black about 0.9 pawns in evaluation. The engine recommends 4...Nc6 instead. If your opponent plays 4...Bf5, you gain a small but real edge — challenge the centre with c4 or develop with Nc3.
Should I play Nbd2 or c3 first after 4...Nc6?
The engine's recommended line goes 5.Nbd2 first, with the idea of meeting ...cxd4 with exd4, keeping the pawn structure symmetrical. You can also play 5.c3, preparing to recapture on d4 with the c-pawn. Both are playable, but Nbd2 is slightly more flexible because it keeps the c3 square open for the c-pawn if needed.
Why does White score worse against 4...Qb6?
The queen sortie to b6 puts immediate pressure on the b2-pawn, which can be annoying to meet. In 63,361 games, White scores only 45.5% against Qb6. The standard antidote is 5.Nc3, defending b2 indirectly by threatening the d5-pawn, or 5.Qc1, protecting the b2-pawn. Once you know the response, the threat is manageable.
How many games feature the London System: c5?
Over 747K Lichess games have reached the London System: c5 position. White wins 47.7%, Black wins 48.3%, with 4.0% draws — based on real rated games.