World chess champion Garry Kasparov has won the third round in his latest attempt to beat a computer at the game.
Kasparov is considered one of the greatest-ever chess players
He and the X3D Fritz program are now level in the Man v Machine challenge after one win each and a draw.
Mr Kasparov stands to earn $200,000 if he wins the final game on Tuesday, but will still get $150,000 if he loses.
The game, held in New York, is being played on a virtual chessboard suspended above Mr Kasparov, who moves the chess pieces by speaking commands.
Mr Kasparov has to wear virtual reality glasses and has a joystick which allows him to rotate the board.
John Fernandez of X3D Technologies, which developed the computer program, said Mr Kasparov had played "perfectly" throughout.
He said: "It was just a dominating performance by Kasparov. He disarmed the computer's biggest weapon, which is its calculating ability."
The 40-year-old grandmaster has played computers before, beating IBM's Deep Blue machine in 1996, but losing a rematch to an upgraded version a year later.
Earlier this year, a series of six games with the Israeli Deep Junior chess program ended in a draw.
The games are being held in New York, with the final game scheduled for 18 November.