Chess World Champ Magnus Carlsen Accuses 19-Year-Old Hans Niemann of Cheating After Controversy

Hans Niemann/Twitter; ARUN SANKAR/AFP via Getty

World Chess Champion Magnus Carlsen has accused 19-year-old Hans Niemann of cheating in a lengthy statement, calling cheating an "existential threat to the game."

In the statement, shared Monday on Twitter, Carlsen, 31, alleged that Niemann "cheated more — and more recently — than he has publicly admitted."

The claim comes after an unsavory conspiracy theory circulated through the chess world after Niemann, an American, defeated Carlsen in a shocking loss at the Sinquefield Cup in St. Louis on Sept. 4, per the New York Times. The third-round loss ended Carlsen's 53-game winning streak in classical tournaments.

"It must be embarrassing for the world champion to lose to an idiot like me," Niemann — who has previously beaten Carlsen in a non-classical match — said after the game. "I feel bad for him."

But the loss wasn't the only dramatic moment of the event.

The following day, 31-year-old Carlsen withdrew from the Sinquefield Cup, something the newspaper noted was a "rare move" among the game's best players such as the Norwegian grandmaster.

"I've withdrawn from the tournament," Carlsen tweeted on Sept. 5. "I've always enjoyed playing in the @STLChessClub, and hope to be back in the future."

In his tweet, Carlsen included a video of Portuguese soccer manager José Mourinho telling reporters he preferred "not to speak" or he would be in "big trouble."

RELATED: Chess-Playing Robot Breaks 7-Year-Old Boy's Finger in Russian Tournament: 'This, of Course, Is Bad'

The clip was filmed after Mourinho's team lost a match where officials were scrutinized for their decision-making, the Times reported. The inclusion of the video in Carlsen's tweet led many to speculate that he was unhappy with his match against Niemann, and perhaps was subtly accusing him of cheating.

Hikaru Nakamura, an American chess grandmaster, also published a 32-minute YouTube video that dived into why he thought Niemann's strategy during the match was unusual and did not rule out the possibility of him cheating.

Chess fans online continued to speculate about how Niemann could have cheated, and eventually, someone put forth the rumor that he could have used a wireless sex toy to have a computer communicate what moves to make.

RELATED: 8-Year-Old Homeless Nigerian Refugee Wins New York State Chess Championship

According to The Guardian, an analysis of the game showed that both players made mistakes, and there were no signs either player was aided by a computer (or hidden sex toys). Yet, Niemann has since been uninvited from the Chess.com Global Championship, the outlet said.

In an interview a few days later following his round 5 match against Leinier Dominguez, Niemann denied the allegations and said he had never cheated in an over-the-board game or a tournament with prize money. Though, he did admit to cheating in an online game when he was 12, something he called a "mistake."

"I'm not going to let Chess.com, I'm not going to let Magnus Carlsen, I'm not going to let Hikaru Nakamura, the three arguably biggest entities in chess, simply slander my reputation because the question is – why are they going to remove me from Chess.com right after I beat Magnus?"

RELATED VIDEO: 'The Queen's Gambit' Star Bill Camp Says He Had Taken Up Chess with His Son Prior to Role

Niemann, who lives in San Francisco, also spoke about his accent — something that some online have called "fake."

"So all these things saying that I'm faking an accent and that I'm putting on some façade, that is like the most ridiculous thing ever said, and anyone using my new-found accent to make any conclusions about anything chess-related is absolutely insane," he said, in part. "I live, I don't spend any time in America, I only speak to chess players who have bad English, so maybe think, maybe I'm a product of my environment."

Soon after Carlsen withdrew from the Sinquefield Cup, he faced Niemann again at the online Julius Baer Generation Cup, but suddenly resigned after making one move.

Carlsen's statement Monday was his first public comment on his matches against Niemann, and he said, "I'm frustrated. I want to continue to play chess at the highest level in the best events."

"I believe that cheating in chess is a big deal and an existential threat to the game. I also believe that chess organizers and all those who care about the sanctity of the game we love should seriously consider increasing security measures and methods of cheat detection for over the board chess."

Carlsen said there was more he wanted to say, but that he couldn't "without explicit permission from Niemann to speak openly."

Niemann has not responded to Carlsen's recent allegations.