Valve’s ongoing Dota 2 tournament had a surprise this year, as an AI took up the task of defeating some of the world’s best players, and succeeded. The bot was designed by OpenAI, a company that is backed by none other than Elon Musk. According to reports, the bot had been trained for only two weeks, yet was able to beat some of the best pros who were at the tournament.

Musk himself tweeted that this is the first time an AI has been able to beat pros at e-sports. It played against Danylo “Dendi” Ishutin, a crowd favourite at the tournament, in a 1-vs-1 match of Dota 2. Dendi was defeated by the bot twice and decided to forfeit future matches with the AI. The bot “feels a little like human, but a little like someone else,” Dendi said, explaining his experience against the AI.

While the feat is perhaps not as big as beating the world’s top Go players, Dota 2 is a complex game in itself. It requires teams of 5 players to compete against each other, in destroying their bases. Dota 2 has a total of 113 playable heroes, each of whom have unique abilities. There are also a myriad number of items in the game, meant to provided added enhancements.