Go at top professional level

Lee Sedol held eighteen international titles; the match was played under standard rules with two hours of main time, and game four was his, after a move AlphaGo had not anticipated. In 2017 AlphaGo Master went 60 to 0 online against top professionals and beat Ke Jie 3 to 0, then AlphaGo Zero surpassed it from self-play alone. Professionals now study engine lines; in 2023 a research group showed that a leading engine (KataGo) could be beaten by an amateur executing an adversarially found blind spot, which is a fragility, not a return of the crown.