World No. 1 Go player Shin Jin-seo beats AI KataGo with a two-stone handicap, ties series

Shin Jin-seo, the world’s top-ranked Go player, did something Sunday that no professional had managed before: he beat KataGo, one of the strongest Go AIs, in an official match with a two-stone handicap. The win ties the three-game series at 1-1, with the final match set for Tuesday.

The match, part of the Jingrui Math · HanKyung Kisin Battle at the Korea Kiwon, ran nearly five hours. On move 290, Shin sealed a 4.5-point victory. Just two days earlier, in game one, he had resigned after 245 moves.

The hardware running KataGo was modest by modern AI standards: four RTX 3090 GPUs with 96GB of VRAM total. Shin played with 5 hours of base time plus one 30-second byoyomi period. KataGo had no base time — it had to compute and play each move within 20 seconds.

Game one showed just how brutal the matchup can be. Shin started with a 99% expected win rate (the handicap advantage), but KataGo threw an unexpected move early. Shin’s advantage began slipping around move 70, and by move 102, the position had flipped. He resigned at move 245.

Game two started the same way — 99% expected win rate, an 18.5-point lead on the board. But this time Shin played differently. He forced a large joseki in the lower right corner, deliberately reducing the amount of open space where KataGo’s tactical superiority could shine. The joseki ran through move 53, occupying nearly a quarter of the board. His win probability held at 99%.

KataGo counterattacked. Hard. Shin absorbed wave after wave of aggressive moves, maintaining his lead past move 150. Then came the middle-game battle. Shin launched an attack on KataGo’s central white group and cut decisively at move 160. His board advantage grew from 6 points to 8, but his win probability dropped to 98% — the first time it had budged. The cut gained territory but complicated the position.

Shin wobbled. His win estimate fell as low as 89% at one point. When he tried to cut again, KataGo responded with a counterattack that caught him off guard. The tension was real. But Shin found the right sequence in the ensuing central fight, playing more precisely than the AI through the critical exchange.

After about four hours and 50 minutes, the game ended. Shin won by 4.5 points.

The final match of the series is on July 21. Shin will likely need to adjust his strategy again — whatever worked Sunday, KataGo’s training pipeline has already incorporated it.