A Japanese badminton star is in danger of being kicked off the team for the Rio Olympics after he admitted to gambling at a casino, local media reported.

Kento Momota took home the country’s first world championship medal in badminton back in August, when he won bronze in Jakarta. But the 21-year-old athlete and his teammate, Kenichi Tago, could be banned from competing in the upcoming summer Olympics if they are found guilty of gambling charges.

Officials from the pair’s team, NTT East Japan, told local media that the two were confirmed to have placed bets at an underground casino that authorities busted in April and May last year.

Located in Tokyo’s Kinshicho area, the establishment—where baccarat was being played—was shut down, and six people, including the casino’s operator, were arrested on suspicion of opening a casino for customers to gamble, the Nikkei Asian Review reported.