GM Garri Kasparov during the third game against Deep Junior in New York Thursday. (Reuters)

New York: A blunder cost chess legend Garri Kasparov the third in a series of Man vs Machine championship games with supercomputer Deep Junior.

“I had a complete blackout,” Kasparov said after the contest. “Despite Deep Junior having a great team and Grandmaster trainers, I had great positions.”

After sacrificing a pawn, Kasparov was left nearly crippled as Deep Junior capitalised on the mistake and prevented any possibility of being checkmated — or having its king captured. Seeing few options to win, Kasparov resigned.

The six-game series is tied at one game each. Kasparov won the first game on Sunday. The second, on Tuesday, was a draw.

Kasparov, 39, said he becomes fatigued during the games, which can last for hours, while the computer doesn’t. “I have to work on that,” he said.

Kasparov rose to prominence as a Soviet junior champion in 1976, at age 12. He has held the world’s No. 1 point-system ranking since 1984, despite occasional losses to human beings, and has achieved almost mythic status in the chess world.

Deep Junior is a three-time world champion and won the last official world chess championship for computers in July.

The match is sanctioned by the world chess federation, which will pay Kasparov $500,000 for playing and another $300,000 if he beats Deep Junior. The supercomputer has not lost a match against a human being in two years.

Experts say it could be tough for Kasparov going into the last three games.

“The question over the next few days is if he can shake off what happened over the last three games and keep playing,” said John Fernandez, a chess consultant for X3d technologies, a sponsor of the match. “Playing an aggressive position is a double-edged sword. If you have the slightest inaccuracy, the computer will exploit the mistake.”

The next game is scheduled for Sunday, one of the two times in the next three games in which Deep Junior will play with white pieces, traditionally seen as an advantage because white makes the first move.

Kasparov lost to IBM supercomputer Deep Blue in 1997. He claimed the computer may have been given hints by human beings, and it was dismantled.