# Week 90: London System vs Accelerated London System, from my side of the board

> Week 90: 1168 to 1177 in four games (2-2). Three 1.d4 d5 2.Bf4 games got three opening names; the Accelerated London one was a win I let slip.

- URL: https://thechesscoach.netlify.app/journey/week-2025-w42/
- Updated: 2026-10-22
- Author: Ignacio Soler

Week 90 (October 14 to 18, 2025) was small: four rapid games, **2 wins and 2 losses**, and my rating moved from **1168 to 1177**. Three of the games were mine as White, and they make a neat little case study of the London System vs Accelerated London System question, at least as far as Chess.com's names go. All three started with the same two moves, 1.d4 d5 2.Bf4. Chess.com called one of them "London System", one "Accelerated London System" and one "Zukertort Variation", depending on what Black played on move 2. The setup I played afterwards was the same each time: Nf3, e3, c3.

## The week in numbers

| | |
|---|---|
| Games | 4 |
| Wins / losses / draws | 2 / 2 / 0 |
| Rating | 1168 → 1177 (+9) |
| Average accuracy | 77.8% |
| Blunders | 6 |
| Most played openings | Queen's Pawn Opening Zukertort Variation (1), London System (1), Pirc Defense (1) |

The two wins were the two cleanest games: 92.7% against benamor007 and 92.6% against Brainpeni. The two losses had all six of my blunders between them, and all six were middlegame moves. One loss was the Accelerated London game, the other a Pirc where my king stayed in the centre, which is starting to feel like a theme after last week.

## London System vs Accelerated London System: what the names hid

Here are the three White games side by side:

- Game 1725 against benamor007 (1192): 1.d4 d5 2.Bf4 e6 3.Nf3. Filed as Queen's Pawn Opening, Zukertort Variation. Win.
- Game 1726 against Brainpeni (1166): 1.d4 d5 2.Bf4 Nf6 3.Nf3. Filed as London System. Win.
- Game 1728 against Ata74 (1202): 1.d4 d5 2.Bf4 a6 3.Nf3. Filed as Accelerated London System. Loss.

So in my games the difference between the London and the Accelerated London is a label set by Black's reply. What decided the results was what happened twenty moves later. The London game had its own small opening lesson, though.

> **Move 5 against Brainpeni: Black's knight had jumped to e4**
> Position (FEN): `rnbqkb1r/ppp2ppp/4p3/3p4/3PnB2/4PN2/PPP2PPP/RN1QKB1R w KQkq - 0 5`
> Played: c3 — Pawn from c2 to c3
> Better: Nbd2 — Knight from b1 to d2, attacking the knight on e4

Against [Brainpeni (1166)](https://www.chess.com/game/live/144313654520) Black put a knight on e4 early. I played my standard 5.c3, and Stockfish called it a mistake (+0.61 to -1.00). Its best reply for Black shows why: 5...g5, a pawn attacking my bishop on f4. If the bishop drops back to g3, it's on a square the knight on e4 also attacks. The engine's 5.Nbd2 challenges that knight at once, before the g-pawn can come. My opponent played 5...a6 instead, a blunder, and I went on to win by resignation on move 37.

## The Accelerated London game I should have won

> **Move 18 against Ata74: Black's rooks were aiming at b2 and c3**
> Position (FEN): `1rr3k1/5pbp/p3p1p1/3p4/P2P4/2P1PNP1/1P4PP/R4RK1 w - - 1 18`
> Played: b4 — Pawn from b2 to b4
> Better: Ra2 — Rook from a1 to a2, protecting the b2 pawn from the side

Against [Ata74 (1202)](https://www.chess.com/game/live/144434807062) I was winning (+3.38). Black's rooks stood on b8 and c8, on open files pointing at my pawns on b2 and c3. The b2 pawn was attacked, so I pushed it: 18.b4. But that pawn was also the one protecting c3. My move had already dropped the evaluation to -0.39, and Black took immediately: 18...Rxc3. Stockfish's 18.Ra2 keeps the pawn where it is and defends it with the rook along the second rank. Two pawns, one protecting the other, and I moved the protector. Stockfish says my winning chance in this game reached 95.7%. It ended as a loss on move 36.

## The Pirc game: castle, again

> **Move 18 against Accidental_Gambit_Player: winning, with my king still on e8**
> Position (FEN): `r3k2r/pnp2pbp/1p2p1p1/4q1B1/2P1Q3/3B1R2/PP4PP/R6K b kq - 1 18`
> Played: Rb8 — Rook from a8 to b8
> Better: O-O — Castling: king to safety, rook into play

As Black against [Accidental_Gambit_Player (1210)](https://www.chess.com/game/live/144367767224), White played an early f4 against my Pirc. By move 18 I was clearly better (-3.08; minus means good for Black) after White's 18.Qe4 blunder. My king was still on e8. I played 18...Rb8, a rook move, and White answered 19.Qc6+, a check along the diagonal to my king, which had to walk to f8 and lost the right to castle. The evaluation went to +1.10 for White. Stockfish's move was simply 18...O-O. In its line White tries 19.Be7 against my rook, but after the trades Black is still winning. I was checkmated on move 28.

## The lesson of the week

Last week I wrote "castle before queen adventures". This week it was "castle before rook moves". The common thread is a king in the centre with the position open, and me spending a move on something else. My second lesson is about protectors: before moving a pawn that's attacked, check what that pawn was defending. On b2 it was guarding c3, and moving it lost both the pawn and the game.

## All games this week

| # | Date | Colour | Opponent | Result | Opening | Accuracy | |
|---|---|---|---|---|---|---|---|
| 1725 | 2025-10-14 | White | benamor007 (1192) | Win | Queen's Pawn Opening Zukertort Variation | 92.7% | [game](https://www.chess.com/game/live/144291841644) |
| 1726 | 2025-10-15 | White | Brainpeni (1166) | Win | London System | 92.6% | [game](https://www.chess.com/game/live/144313654520) |
| 1727 | 2025-10-16 | Black | Accidental_Gambit_Player (1210) | Loss | Pirc Defense | 68.8% | [game](https://www.chess.com/game/live/144367767224) |
| 1728 | 2025-10-18 | White | Ata74 (1202) | Loss | Queen's Pawn Opening Accelerated London System | 57.3% | [game](https://www.chess.com/game/live/144434807062) |

Previous week: [week 89](/journey/week-2025-w41/). Next week: [week 91](/journey/week-2025-w43/). Every week is collected on the [journey page](/journey/). The evaluations and move descriptions come from Stockfish, the same way Chess Coach handles it when you [review your own games like this](/features/ai-chess-analysis/).

## FAQ

### What is the difference between the London System and the Accelerated London System in my games?

Only the label. All three of my White games this week started 1.d4 d5 2.Bf4, and Chess.com named them London System, Accelerated London System and Zukertort Variation depending on Black's second move (...Nf6, ...a6 and ...e6).

### Which one did better for me?

The game labelled London System was a win at 92.6% accuracy. The game labelled Accelerated London was a loss, even though Stockfish says my winning chance reached 95.7% in it.

### What went wrong in the Accelerated London game?

On move 18 I played b4 while Black's rooks were on b8 and c8. The pawn on b2 had been protecting c3, and after b4 Black took it with 18...Rxc3. Stockfish preferred 18.Ra2, protecting b2 from the side.

## Related

- [From 631 to 1385: my chess journey in 2,117 games](https://thechesscoach.netlify.app/journey.md)
- [Week 89 (Oct 2025): Pirc Classical, and I forgot to castle](https://thechesscoach.netlify.app/journey/week-2025-w41.md)
- [Week 91 (Oct 2025): Pirc vs Modern Defense, 0-3 against 4-0](https://thechesscoach.netlify.app/journey/week-2025-w43.md)
- [Free AI chess analysis of your games, explained](https://thechesscoach.netlify.app/features/ai-chess-analysis.md)