South Korean Go master Lee Sedol, 36, has officially stepped down from competing. Lee started playing the Chinese strategy board game (战略性棋盘游戏) when he was just 6 years old. He then joined the professional league at the young age of 12. In March 2016, Lee shocked the world after he confronted (对抗) the artificial intelligence (人工智能) Go player, AlphaGo, designed by Google. Although Google’s algorithm (算法) won four of the five games, Lee’s win was the first and only time a human beat AlphaGo. Despite his professional success, Lee was planning to retire since his loss against his Chinese rival (对手) , Ke Jie, back in March. “I thought it’s going to be more difficult to beat these young Go players. Personally, I also feel exhausted,” Lee said.