London System traps: 6 mistakes at 2000-2200 Elo

October 9, 2026 · 4 min read

At 2000-2200 most players know their London lines by heart, and both sides find the basic tactics. The mistakes that remain are about move order: a natural developing move one tempo too early, a bishop that attacks the queen without a guard, or a recapture that hands the other side an open line.

We took the Lichess blitz and rapid games from August 2026 where both players were rated 2000 to 2200, followed the London move by move, and had Stockfish check every position where many players took the same wrong turn. Every line below was verified by the engine. All six examples are told from White’s side. For the main ideas of the opening, read our London System guide. One level down, see 6 mistakes at 1800-2000 Elo.

Part 1: punish it

Three Black mistakes, three punishments. At this level, most White players found them. The point is to know why they work, so you find them too.

1. 5...Nc6 before ...a6

After 1.d4 d5 2.Bf4 Nf6 3.e3 e6 4.Nf3 c5 5.Nc3, half of the Black players, 50%, develop with 5...Nc6. But with the bishop on f4 already aiming at c7, the knight jump 6.Nb5! is a real threat: Nc7+ forks the king and the rook. After 6...cxd4 7.Nc7+ Kd7 8.Nxd4 e5 9.Nxc6 Qxc7 10.Nxe5+, White is a pawn up and the black king is stuck in the middle. 16 of the 17 White players found 6.Nb5.

Black should play 5...a6 first, to take b5 away from the knight. The game is balanced.

5...Nc6? and 6.Nb5! hits c7.

2. 7...Bf5, and the bishop has no guard

After 1.d4 d5 2.Bf4 Nf6 3.e3 c5 4.c3 Nc6 5.Nd2 Qb6 6.Qb3 c4 7.Qc2, 13% of Black players attack the queen with 7...Bf5. But nothing defends f5. 8.Qxf5! simply takes the bishop. Black grabs pawns with 8...Qxb2 9.Qb1 Qxc3 10.Ne2 Qb4 11.a3 Qxb1+ 12.Nxb1, but White is a piece up for two pawns. 4 of the 5 White players took on f5.

Black should play 7...g6 or 7...Nh5 instead, and the game is balanced.

7...Bf5? and 8.Qxf5! wins a piece.

3. 4...Bxf4 against the early Qg4

After 1.d4 d5 2.Bf4 e6 3.e3 Bd6 4.Qg4, 25% of Black players take the bishop with 4...Bxf4. It looks like a normal trade, but the queen on g4 was already hitting g7. White does not take back: 5.Qxg7! hits the rook on h8 first. After 5...Qf6 6.Qxf6 Nxf6 7.exf4, White has the piece back and an extra pawn, and Black’s kingside is broken. 4 of the 5 White players found 5.Qxg7.

Black should guard g7 with 4...g6 instead, and the game is balanced.

4...Bxf4? and 5.Qxg7! wins a pawn.

Part 2: avoid it

Now the White mistakes that come up most in the London at 2000-2200. None of them loses on the spot. Each one gives Black an easy game: time, a diagonal, or an open file.

4. 4.Qxd4 after ...c5 and ...cxd4

After 1.d4 Nf6 2.Bf4 c5 3.c3 cxd4, 13% of White players take back with 4.Qxd4. But the queen in the center is a target. 4...Nc6! develops with tempo, and after 5.Qa4 e5 6.Bg3, the queen has moved twice and Black has the center. Black is better.

Play 4.cxd4 instead. Take back with the pawn, keep the center, and the game is balanced.

4.Qxd4? and 4...Nc6! Play 4.cxd4 instead.

5. 6.c4 against the King’s Indian setup

After 1.d4 Nf6 2.Bf4 g6 3.e3 Bg7 4.Nf3 O-O 5.Nbd2 d6, 8% of White players grab space with 6.c4. But that leaves b2 without the c3 pawn in front of it. 6...c5! opens the long diagonal. After 7.d5 Nh5 8.Bg5 Bxb2 9.Rb1 Bg7, Black has won the b2 pawn and is better.

Play 6.c3 instead. The pawn blocks the bishop on g7 and keeps d4 solid. The game is balanced.

6.c4? and 6...c5! Play 6.c3 instead.

6. 7.Qxb6 after ...c4

After 1.d4 d5 2.Bf4 Nf6 3.e3 c5 4.c3 Nc6 5.Nd2 Qb6 6.Qb3 c4, 17% of White players trade queens with 7.Qxb6. It looks safe, but 7...axb6 opens the a-file for the rook on a8 and puts a second pawn on the b-file, ready for ...b5. Black is a little better in the endgame. The mistake is small, but it gives away White’s edge for nothing.

Play 7.Qc2 instead. Keep the queens, aim at f5, and White is slightly better.

7.Qxb6? and 7...axb6. Play 7.Qc2 instead.

What to take away

When the bishop on f4 already hits c7, a knight on b5 is a threat, not a hope.
A black bishop that attacks your queen without a guard can often just be taken.
Against an early Qg4, check what happens to g7 before you take the bishop on f4.
Before you trade queens or push c4, ask which file or diagonal you are opening for Black.

These patterns come from many games between players at your level, not from a theory book. Your own games have patterns too, and they are probably not the same ones. Chess X-Ray finds the moves where you lost your advantage in your chess.com or Lichess games, groups them by opening, and turns them into lessons you replay until they stick.