Hans Niemann, the teenage American grandmaster at the centre of an alleged cheating scandal, has sued world champion Magnus Carlsen, online platform Chess.com and others for slander and libel.
Nieman is seeking at least $175 million in damages.
Photo: Gladson Xavier/Pexels
Niemann, 19, claims the defendants are "colluding to blacklist" him from the professional chess world and that he has been shunned by tournament organisers since five-time world champion Carlsen publicly accused him of cheating.
Carlsen's surprise defeat to Niemann and his subsequent withdrawal from tournaments has sparked a furore of comments and allegations that the American had cheated.
Weeks after the Sinquefield Cup touornament, the Norwegian resigned after just one move against Niemann in an online tournament and said later in September he believed the American had "cheated more - and more recently - than he has publicly admitted".
In a statement on Thursday, lawyers for Chess.com said there was no merit to Niemann's allegations and that the company was saddened by his decision to take legal action.
"Hans confessed publicly to cheating online in the wake of the Sinquefield Cup, and the resulting fallout is of his own making," the statement read.
"Chess.com looks forward to setting the record straight on behalf of its team and all honest chess players."
Chess.com banned Niemann after the first match against Carlsen and published a report earlier this month that said he had likely cheated more than 100 times in online games.
Niemann had previously been banned from Chess.com for cheating online, having admitted he had not played fairly in non-competitive games on the website in his youth, but denied any wrongdoing while contesting over-the-board games.
The International Chess Federation (FIDE) said last month it would open an investigation into the allegations of cheating.
-Reuters