An OpenAI bot trained entirely through self-play defeated professional player Dendi in a 1v1 Dota 2 match on the main stage of The International. Learning from scratch without imitation learning or tree search, the bot had also gone undefeated against several top professionals, including SumaiL, in the preceding week. Reaching this level in a complex game that plays out in real time, rather than a turn-based one like Go or chess, was a substantial result at the time.