Shin Jin-seo, the world's top Go player, recently made history by defeating the advanced artificial intelligence (AI) KataGo in a three-game match during the Ssen Math-Hankyung Gisin tournament in South Korea. The matches took place on July 17, 19, and 21, 2026. In a gesture meant to level the playing field, Shin was given an initial advantage by starting with two pre-placed stones on the board—a concession often used to compensate for the perceived skill gap between human players and AI systems. In the first game, which lasted 245 moves, Shin Jin-seo was surprised by KataGo's use of an unfamiliar strategy. Despite months of preparation, he admitted that "a month of preparation was lost in a single move" when he ultimately conceded defeat. However, in the second game, which stretched to 290 moves and nearly five hours, Shin turned the tide in his favor. He repeated this success in the third game, which ended after 221 moves and about 3 hours and 20 minutes. Shin attributed his victories to KataGo's tendency to play conservatively when facing a deficit. Unlike human players, who often take calculated risks to change the course of the game, KataGo's cautious approach allowed Shin to outmaneuver the AI. This strategy, while effective in maintaining stability, proved to be a vulnerability in the match. Despite the initial advantage given to him, Shin Jin-seo's victory is considered a significant milestone. It marks the first time a human has officially defeated KataGo under these specific conditions, highlighting the ongoing challenges and complexities of human versus AI competition in the intricate game of Go.