Post-mortem of a fourth-round loss: three decisions, one bad

1.The position after the opening

We reached a symmetrical queen's pawn structure by move ten, the sort of position where nobody has anything and both players know it. I had the slightly freer bishop, my opponent had a half-open file, and the pawns were level. My clock said fifty-two minutes to his forty-eight, which for me is unusually healthy. Written down like that it sounds like a decent start, and it was. Everything that follows happened in the next fifteen moves, all of them quiet.

My opponent was rated something over two hundred points above me, and the useful thing about that evening is that he never did anything I could point at afterwards as clever. He made small, obvious, slightly annoying moves, kept the position balanced, and waited. That is the part of playing stronger opponents that nobody warns you about: there is no moment where you are beaten. There is a sequence of reasonable-looking choices, and at the end of it your position is worse and you cannot say exactly when it happened.

2.Decision one: the pawn I did not take

On move fourteen I could have taken a pawn on the queenside and accepted a ragged structure in return. I spent eleven minutes on it, counted three ways in which my king would be draughty afterwards, and declined. Walking home I was sure this was the losing decision, and I said so to a teammate on the platform with the confidence of a man who has just lost. Four passes through the game later, I think declining was correct, or at worst a matter of taste.

What was wrong was the eleven minutes. The position after taking was complicated enough that I would have had to calculate it properly to play it well, and I did not have the clock for that at move fourteen. The decision itself was defensible; the price I paid for it was not. Somewhere in that eleven minutes I also stopped looking at what my opponent wanted, which is the habit I have been trying to build for two years and which disappears the moment a concrete option is on the table.

3.Decision two: the trade I wanted

Three moves later I traded my good bishop for his knight, because the knight had been sitting on a square I disliked and because trades feel safe when the clock is uneven. It was not a blunder. It was a small concession that removed my only real asset and left me with a position where I had nothing to do and he had a slow plan. Those positions are not lost. They are, for a player of my strength against a player of his, a long afternoon of not quite drowning.

The engine calls the trade roughly equal, which I have learned to read carefully. Equal in the engine's sense means the position holds if you play it well for another thirty moves. Equal in my sense should mean I know what I am doing next. After that trade I did not, and the notebook entry from the same evening says exactly that in fewer words: traded because I did not like his knight, not because I wanted the resulting position.

4.Decision three, and the real mistake

The mistake I now think decided the game came on move twenty-six and took me under a minute. I had a choice between passive defence on the second rank and giving up a pawn to activate my rook. I defended, because it was cheap and because I had eighteen minutes left against his thirty and did not want to think. Two moves later the same option was gone. From there he needed twenty more accurate moves and he had all evening to find them.

The pattern across all three decisions is the same and it is not about chess knowledge. I spent my time on the decision that felt dangerous and almost none on the decision that mattered, because the second one did not feel like a decision at all. It felt like tidying up. What I have changed since is small: when a move is cheap and obvious, I make myself name the alternative out loud in my head before playing it. It costs thirty seconds and has already saved one half point.

• Eleven minutes on move fourteen, under a minute on move twenty-six.
• The bad move was the fast one, both times I checked.
• Engine equality is not the same as knowing what to do.
• Name the alternative before playing the obvious move.