A mysterious online Go player known only as “Master” has astonished professional competitors after winning more than 50 games against highly ranked opponents in just over a fortnight.

On Tuesday, Master beat Ke Jie, a 19-year-old Chinese prodigy who currently tops worldwide rankings for the ancient board game also known as weiqi.

Ke has been widely anticipated to face off against Google’s artificial intelligence player AlphaGo, though a date has not yet been set for the match. In March 2016, AlphaGo beat Lee Se-dol, a world champion from South Korea, in a matchup closely followed in China. Many players, including Ke, speculate that Master, too, is an AI player.

Master first appeared in the Chinese Go community on Dec. 19 on Yicheng, a popular online platform for high-level Go players to practice outside of professional competition. Master won against several top players, including 19-year-old Yu Zhiying, the world’s highest-ranked female Go player.

The newcomer’s success and unusual game strategy attracted enormous attention among other players. “After Master won several games against online players, we became aware that it wasn’t human,” Yu told Sixth Tone. “Its way of thinking is unexpected, and it really is more powerful than human beings.”

The game Yu lost to Master was a “quick match” that required players to make each move within 20 seconds. Other quick matches have the timer set at 30 or 60 seconds, while in “slow match” Go, players have up to three hours to finish a game and no time limit on individual moves.

So far, Master has only played quick games, leading players to wonder if slow matches may be the last hope for humans competing against machines.

On Dec. 31, just a few days before he played against Master himself, Ke posted on his Weibo microblog saying that he’d been studying AI players’ strategy and gameplay since March. “After thousands of years of human practice and progress, computers seem to tell us we’ve got it completely wrong. I think that not a single person can get to the edge of Go’s truth,” he wrote. “But I want to say, from now on, we players will join with computers to step into a brand-new realm, to reach new frontiers. A storm is brewing; I will bring all of my wisdom to the ultimate battle!”

On Monday, Master registered on another online Go platform, Yehu — or “wild fox” in English — and beat a famous Chinese Go player, Gu Li, who then posted on Weibo saying that he would reward anyone who beat Master on the platform with 100,000 yuan ($14,400). When Ke lost on Tuesday, the competition between human and AI players again began to garner public attention. A number of Chinese news websites have live-broadcasted Master’s games.

By Wednesday afternoon, Master had won 54 games, including one against Nie Weiping, a veteran champion whose fame has made him a household name in China. The newcomer’s identity remains a mystery — unlike Google’s prized creation AlphaGo, no person or organization has claimed Master as their own. Some players have hypothesized that Master is, in fact, an updated version of AlphaGo.

Most professional Go players are more excited than disappointed by the appearance of Master. AlphaGo has only played 13 public games that players can review and study, while Master has already played more than 50 against over a dozen human competitors — winning all except for one game that ended in a draw when the human player lost his internet connection.

“AlphaGo didn’t leave us with many move records, but this time, more expert players have the opportunity to learn from a high-level AI opponent,” professional Go player Zhong Wenjing told Sixth Tone. “Master’s records are available to the public, and everyone can have a look and learn from its advanced strategy. Sometimes I can understand its logic, but sometimes I can’t make sense of it based on my own thinking.”

(Header image: South Korean Go game fans watch a live broadcast of the Google DeepMind Challenge Match at the Korea Baduk Association in Seoul, March 9, 2016. JUNG YEON-JE/AFP/VCG)