‘FRITZ punishes you immediately for that,” Vladimir Kramnik said before his $1 million match with Deep Fritz. After all, the computer can visualize more than 8 million positions per second, he said.

The “that” he referred too was illogical play – but Kramnik was soon punished for something far worse.

On the 34th move of the second match game, he made perhaps the worst move ever seen in a world-class event. He allowed Deep Fritz to deliver checkmate in one move.

The position wasn’t remotely difficult. The computer only had two pieces, a queen and a knight, plus four pawns. And Kramnik had plenty of time – half an hour to make his next seven moves.

“I can’t explain it,” he said at a press conference. “I rechecked this variation many times and analyzed quite far ahead. It seemed to me I was winning.”

In reality, his advantage had dissipated and his 34th move should have been a king move that would have made a draw likely.

It’s been nearly 80 years since a player allowed mate in one in a world championship match.