Having become the first computer in history to defeat a top-ranked human player of Go yesterday, Google's artificial intelligence (AI) program, DeepMind, has proved it wasn't a fluke by winning the second of five matches against world champion Lee Sedol.
DeepMind Technologies was founded in 2010 by Brits Mustafa Suleyman and Demis Hassabis, and New Zealander Shane Legg, who Hassabis met at University College London's Gatsby Computational Neuroscience Unit.
Using AI, the start-up built a computer that mimics the short-term memory of the human brain.
In 2014, Google acquired the company for £400 million and renamed it Google DeepMind, but it has remained headquartered in London.
While AlphaGo defeated Sedol by resignation after 186 moves in the first match, this time the world champion held until the final period of overtime before finally giving up.
"Yesterday I was surprised but today it's more than that – I am speechless," Sedol commented after the match. "I admit that it was a very clear loss on my part. From the very beginning of the game I did not feel like there was a point that I was leading."
Hassabis added: "We're very pleased that AlphaGo played some quite surprising and beautiful moves, according to the commentators, which was amazing to see."
During the match, the commentators noted that some of AlphaGo's moves seemed peculiar, but they ultimately proved decisive in the result of the match.
The overall victor after the five matches will win $1 million. If DeepMind wins, it will donate the money to charity.
Go is an ancient Chinese board game in which the aim is to surround more territory than the opponent. It is renowned for its complexity because of the trillions of possible moves.
The games are taking place each day this week in Seoul at 1pm Korean time (4am GMT), and are being live streamed via YouTube.
"Lee Sedol is the greatest player of the past decade," Hassabis commented when the match was announced earlier this year. "I think that would mean AlphaGo would be better than any human at playing Go. Go is the ultimate game in AI research."
IBM made headlines when its AI computer Deep Blue defeated chest grandmaster Garry Kasparov in 1997, but chess only has around 10 to the power of 60 possible ways a game can be played, compared to 10 to the power of 700 possible scenarios in Go.
Suleyman celebrated AlphaGo's second victory on social media: "Wow! #AlphaGo wins a second time!" he tweeted. "Completely surreal… Huge respect for Lee Sedol. Amazing battle!"