Teenage American Grandmaster Hans Niemann has offered to "strip naked" to prove he is not a chess cheat, angrily dismissing suspicions surrounding his upset win over five-time world champion Magnus Carlsen.
The 19-year-old admitted to cheating in online chess games as a child, but said his play was now completely above board.
"Do any fair play checking you want, I don't care because I know that I'm clean," he said in a video interview with chess commentator Alejandro Ramirez.
"They want me to strip fully naked? I'll do it. I don't care because I know I know that I'm clean and I'm willing to subject myself to what you want me to play," Niemann said.
The Sinquefield Cup has already implemented additional anti-cheating measures – such as using metal detectors on players and putting matches on a 15-minute broadcast delay – after Carlsen sensationally pulled out of the $500,000 event in Saint Louis following his shock third-round loss to Niemann.
Carlsen announced his withdrawal via a cryptic tweet on Tuesday morning (AEST) which was interpreted by many commentators – including leading American grandmaster Hikaru Nakamura – as alluding to foul play.
Live-streaming to thousands of his followers on Twitch, Nakamura said: "I think Magnus probably believes Hans is cheating".
Nakamura also revealed his compatriot had previously been banned from the chess website Chess.com, which Niemann himself has now confirmed.
"I cheated on random games on Chess.com — I was confronted, I confessed," said Niemann, who said this happened when he was 12 and 16.
"This is the single biggest mistake of my life and I am completely ashamed, and I'm telling the world because I don't want misrepresentations and I don't want rumours.
"I have never cheated in an over-the-board game."
Niemann said that following Carlsen's withdrawal from the Sinquefield Cup, his access to Chess.com had again been revoked and he had been uninvited from its Global Championship.
Chess.com announced last month that it was in the process of taking over Carlsen's "Play Magnus Group" in a $122 million merger.
"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," said Niemann.
"Chess.com has suddenly decided to hop on Magnus's insinuations and Hikaru's very direct accusations. I believe this is completely unfair — this is a targeted attack.
"They know I am not a cheater and that I give everything to chess. I work so hard and chess is my entire life."
