Google's DeepMind AlphaGo artificial intelligence has defeated the world's number one Go player in a three-game series.
The computer took out the second game against China's Ke Jie at the Future of Go Summit being held by Google in Wuzhen, China.
Jie got off to an almost perfect start but the AI pulled through in the end.
"For the first 100 moves it was the closest we’ve ever seen anyone play against the Master version of AlphaGo," DeepMind CEO Demis Hassabis said after the match.
But AlphaGo pulled through, leaving its vanquished opponent confused and ultimately disappointed.
"AlphaGo made some moves which were opposite from my vision of how to maximize the possibility of winning," Ke said.
"I also thought I was very close to winning the game in the middle but maybe that’s not what AlphaGo was thinking. I'm a little bit sad, it’s a bit of a regret because I think I played pretty well."
Although the series has already been won the final game will be played on Saturday.
In Go, players take turns placing stones on a 19-by-19 grid, competing to take control of the most territory.
It has long been a subject of interest for computer scientists, attracted by the game's complexity and enormous number of potential moves.
AlphaGo became a master of the game by studying older matches and playing thousands of games against itself.
Deepmind, which Google acquired in 2014, hopes the AI behind AlphaGo will eventually have applications "in areas of medicine and science".