World No. 1 Shin Jin-seo, 9-dan, pulled off a come-from-behind win against KataGo, one of the strongest go AIs available.
On the 21st, at The Korea Economic Broadcasting studio in Jung-gu, Seoul, Shin Jin-seo defeated KataGo by 11.5 points after 221 moves in the final game of the three-game "Ssen Math·Hankyung Gisinjeon." After losing Game 1, he took Games 2 and 3 in a row to finish the series at two wins and one loss.
This match was played as a handicap game in which Shin Jin-seo, as Black, placed two stones first. With an 18.5-point advantage, he began the deciding Game 3 with an expected win rate of 99%.
Unlike in Games 1 and 2, KataGo opened at the upper-left corner komoku for its first move, choosing a new opening pattern. After responding cautiously early on, Shin Jin-seo continued a strategy of avoiding major fights and securing territory safely. He had said before the event, "I will minimize fighting and decide it by territory."
The game turned in the middle game. Shin Jin-seo consolidated his lead by building a large Black framework connecting the top side and the center, and he continued to manage the game stably afterward. In Games 1 and 2, his overwhelming leads—reaching a 99% win rate—wobbled at the end, but on this day he held the lead to the finish. After about 3 hours 20 minutes and 221 moves, he scored a convincing win by 11.5 points.
Even before the match, many in the go world predicted it would be a success if Shin Jin-seo won even one game. At a press conference after the match, Shin said, "Abandoning my style completely and playing defensively was not an easy process," adding, "Although the content was better in Game 3, the most satisfying game was Game 2, where I overturned a difficult contest."
On KataGo, he said, "AI's pursuit of perfection can actually be a weakness," noting, "Even when the position worsens, it doesn't throw in a fighting move." He added, "What's appealing about human go is the ability to play fighting moves and ingenious tesuji depending on the situation," and said, "It was meaningful in showing that we can hold our own even against AI."
In this match, Shin Jin-seo had a five-hour main time with a single 30-second byoyomi, while KataGo played without an overall time limit but had to move within 20 seconds each turn. KataGo's moves were computed on a dedicated system built on Tygem, and Lee Dan-bi, 1-dan, of the Korea Baduk Association, placed the stones on its behalf.
With the overall victory, Shin Jin-seo received 250 million won in prize money, including appearance fees, and a Genesis G90 as a prize.