World No. 1 Go player Shin Jin-seo falls to KataGo in series opener despite two-stone handicap

Shin Jin-seo, the world's top-ranked Go player, suffered a defeat against AI program KataGo despite receiving a two-stone handicap in the opening game of a three-match series on Friday.

The match marks the 10th anniversary of Go master Lee Se-dol's historic match against AlphaGo, in which Lee became the only human to defeat the AI in one of five games.

Shin, playing as Black, resigned after 245 moves against KataGo, which played as White, in the first game.

The three-game series adopted a two-stone handicap in recognition of the AI's overwhelming computational capability. Under the handicap, the human player begins with an estimated advantage of 18 points.

At a media day event on Tuesday, Shin said he chose the two-stone handicap because "humans simply cannot beat AI in an even game, while I think three stones would give me the advantage."

"I'll avoid fighting as much as possible and try to protect the 18-point advantage until the end," he added.

But Shin's defensive strategy was thrown off by the AI's second move. Instead of approaching Black's stone in the upper-right corner or extending along the right side — which would be moves commonly seen in human play — KataGo placed a White stone in an unconventional three-space approach.

"That move alone may have been about a one-point mistake," Shin said after the game. "But that single move made all of my preparation over the past month useless. It caught me off guard from the beginning, and I don't think I was ever able to play the game the way I wanted."

Despite the early surprise, Shin tried to hold on to his two-stone advantage through the middle of the game. But during a fierce battle along the lower side of the board, KataGo gained the upper hand. On Black's 103rd move, Shin attempted to split White's central and lower-side groups. At that moment, the win probability swung in White's favor for the first time.

KataGo then precisely struck a vital point in Black's lower-right corner formation with a second-line placement, capturing five Black stones.

Shin made one final attempt with a ko fight along the top side of the board, but the gap only widened. When he resigned after 245 moves, the win probability showed White ahead by 28.8 points with 1 hour 50 minutes and 59 seconds remaining out of the game's five-hour time limit.

Shin received only the 50 million won ($33,650) appearance fee after losing the opening game. A victory would have earned him an additional 50 million won as a win bonus.

The player's second game against KataGo will be played on Sunday, and the third game on Tuesday.

BY SON MIN-HO [[email protected]]