The shocking defeat of one of the best chess players in the world sparked accusations of cheating and has thrown the sport into a tailspin over the last few weeks.

Magnus Carlsen, the 31-year-old chess grandmaster who was unbeaten entering the Sinquefield Cup, lost to upstart American player Hans Niemann last week, ending the top-ranked Chess player’s 53-game winning streak. After the loss, Carlsen tweeted he was withdrawing from the tournament, hosted by the St. Louis Chess Club.

"I've withdrawn from the tournament. I've always enjoyed playing in the @STLChessClub, and hope to be back in the future," he wrote, adding a link to a 2020 video from soccer manager Jose Mourinho who famously said after a match, "If I speak, I am in big trouble."

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Magnus Carlsen in Denmark

Norwegian chess player Magnus Carlsen participates at the Energy Denmark Champions Battle 2019 in Circus Building, Copenhagen, Denmark May 22, 2019. (Claus Bech/Ritzau Scanpix/via REUTERS)

Niemann, 19, immediately faced accusations of cheating – from anything to wireless vibrating anal beads to a vibrating shoe, according to multiple reports. Tesla CEO Elon Musk even added to the controversy with a tweet of his own, suggesting something was in Niemann’s butt during the match. A professional game also suggested something like that as well.

Niemann denied cheating in an interview with the Chess Club.

"I have never cheated in an over-the-board game. That is the worst thing I could do: cheat in a tournament with prize money," he said, via KSDK-TV.

"You know my dream came true. I lived my dream for a day beating Magnus, and then, all of this happened."

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St. Louis Chess Club Executive Director Tony Rich told the station there have been anti-cheating measurements in place for the tournament. According to the Guardian, Niemann was also frisked before the match.

According to the International Chess Federation ratings, Niemann was No. 49 in the world with a 2688 rating. Carlsen was No. 1 with a 2861 rating.

Chess pieces

Pieces stand on a chess board at the Werner Ott Open of the Kreuzberg Summer at the Berlin Kreuzberg Chess Club. (Andreas Gora/picture alliance via Getty Images)

Niemann finished in seventh place in the tournament.

The young chess player was also banned from Chess.com and uninvited from the Global Championship, according to the Guardian. The website told the New York Post that Niemann was banned for cheating on the website.

"We have reached out to Niemann to explain our decision to privately remove him from Chess.com and our events. We have shared detailed evidence with him concerning our decision, including the information that contradicts his statements [about] the amount and seriousness of his cheating on Chess.com," a spokesperson for the website told the New York Post.

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The two players are both set to participate in the Julius Baer Generation Cup this weekend.