He is the world's top player of an ancient Chinese board game called Go, known for his tendency to turn games around at the last minute.
This afternoon, South Korean Lee Se Dol, 32, will be pitting his mind against a Google-developed artificial intelligence (AI) program in a highly watched Go match that could mark a significant milestone in the man-versus-machine debate.
Addressing the media in Seoul yesterday, Mr Lee admitted that he felt more nervous after watching a presentation during the press conference that showed how Google's AlphaGo is programmed to narrow down millions of possible moves and mimic a human player's thought processes.
He thinks he would still be able to win the five-day match due to end next Tuesday, but "maybe I will not get a 5-0 victory". That was the score he predicted last month.
Created by Google's AI development arm DeepMind, AlphaGo made history last October by becoming the first computer to defeat a professional Go player, a decade earlier than earlier predictions.
It won 5-0 against European champion Fan Hui, a Chinese-born two-dan player (on a professional scale of one to nine) who is ranked 800th in the world.
Mr Lee, in comparison, is a nine-dan player with 18 international titles under his belt. He turned pro at the age of 12 and is currently ranked the best in the world.
DeepMind founder Demis Hassabis said his team has made improvements to AlphaGo since the match with Mr Fan, and is waiting to see how it will fare against the "brilliance and creativity of Lee Se Dol".
"No matter the results of the match, it's a testament to the power of human ingenuity," he said.
Behind AlphaGo's development lies the desire to push frontiers in AI research. Its underlying principles and learning algorithms can be applied to make phones smarter and help in robotics development, said Mr Hassabis. But there is a lot more research to be done before it can be implemented, he added.
Go is a game with simple rules, played with black and white stones on a board with the aim of surrounding and capturing the opponent's stones. What makes it complex is that there could be more board configurations than atoms in the universe, and the key to winning is intuition and creativity.
For Mr Lee, it was curiosity that led him to agree to the match. He said he accepted the challenge in less than five minutes as he was curious how a computer would play against him. A big part of the game involves analysing the opponent's strengths and observing how he plays. But this time, he has been preparing by playing games in his mind, up to two hours a day.
"One lost game won't matter to the entire Go community, but it will be a very important milestone in the history of artificial intelligence, so I'll try my best to win," he said.
The opening match today will be streamed live on DeepMind's YouTube channel from 1pm Korea time (noon Singapore time).