Niemann, who has been embroiled in a cheating scandal, is seen playing in St. Louis last month.
CNN  — 

Chess grandmaster Hans Niemann said he is “not going to back down” as accusations of widespread cheating intensify.

On Tuesday, an investigation by popular online platform Chess.com claimed Niemann “likely cheated” in more than 100 online matches, a week after world champion Magnus Carlsen explicitly accused the American of cheating in over-the-board games.

The 19-year-old Niemann has only admitted to cheating twice in his chess career at the ages of 12 and 16, and on Wednesday said his “chess speaks for itself” after defeating Christopher Yoo in the first round of the US championship in St. Louis.

“This game is a message to everyone,” Niemann said after his victory. “This entire thing started with me saying chess speaks for itself and I think this game spoke for itself and showed the chess player that I am.

“It also showed that I’m not going to back down and I’m going to play my best chess here regardless of the pressure that I’m under.”

After giving just one answer, Niemann ended his post-game interview by saying “it was such a beautiful game I don’t even need to describe it.”

He next faces Jeffery Xiong in the second round of the US championship, which runs until October 20.

According to the report by Chess.com, Niemann privately confessed to cheating to the website’s chief chess officer in 2020, which led to him being temporarily banned from the platform.

The report said Chess.com closed Niemann’s account in September given his previous acknowledgments of cheating, suspicions about his recent play and concerns about the steep, inconsistent rise in his rank.

“While we don’t doubt that Hans is a talented player, we note that his results are statistically extraordinary,” the report said.

CNN has previously contacted Niemann regarding the allegations in the report.

Carlsen first made explicit allegations of Niemann’s cheating after two incidents between the pair – the first when Carlsen withdrew from last month’s Sinquefield Cup after a defeat against Niemann, and the second when he quit their match at the Julius Baer Generation Cup after making just one move.

The Norwegian said he believes that his rival “has cheated more – and more recently – than he has publicly admitted” and that “his over the board progress has been unusual.”

“Throughout our game in the Sinquefield Cup I had the impression that he wasn’t tense or even fully concentrating on the game in critical positions, while outplaying me as black in a way I think only a handful of players can do,” Carlsen added.

FIDE, the sport’s global governing body, said it would launch an investigation following Carlsen’s claims.