One of Google's top computer programmes squared off against a human opponent for a five-round match of the boardgame Go on Wednesday, in the latest development to pit artificial intelligence against human ingenuity.
"If I make mistakes, I could lose," world champion Lee Sedol admitted the day before.
"I'll do my best to win 5-0, but people make mistakes," Lee said. The 33-year-old professional Go player is fighting Google's AlphaGo software for a prize of 1 million dollars.
Bookmakers were offering odds of around even for the two opponents.
The rules of the boardgame Go, which originates in China, are easy in principle: Two players try to conquer spaces with white and black stones on the board, which is divided by vertical and horizontal lines into a grid.