Czech beach volleyball player Ondrej Perusic has returned a positive COVID-19 test at the Olympic Village in Tokyo, the Czech Republic's Olympic Committee said.
The result comes after officials said on Saturday that a Czech team staff member had tested positive for COVID-19 after arriving in Tokyo on a charter flight from Prague.
"Unfortunately, beach volleyball player Ondrej Perusic has a positive finding from a sample taken during daily testing in the Olympic village on Sunday," Martin Doktor, sports director of the Czech Olympic Committee, said in a statement.
"It is still fresh information and everything is evolving quickly. We are solving details, including the sport impact."
Perusic, 26, was due to play his first match on July 26, which the team said was now unlikely due to isolation requirements
Elsewhere, an American alternate gymnast has also tested positive for COVID-19, but the main team has moved to separate accommodation and is continuing preparation for the Olympics, USA Gymnastics confirmed.
A Japanese official had earlier said one member of the US' gymnastics delegation in her teens had tested positive and had one close contact, but declined to give further details.
"One of the replacement athletes for the women's artistic gymnastics team received a positive COVID test on Sunday, July 18," USA Gymnastics tweeted.
It added that the local government had determined that the athlete, whose name wasn't given, and one other replacement athlete needed to be subject to further quarantine, so the rest of the team has moved to alternative accommodation and will continue preparing for the Games.
Multiple Japanese media reports said that a simple saliva screening test had flagged the athlete concerned as a suspected positive, and it was confirmed with a more detailed PCR test on Monday.
They added that this person and one close contact were remaining at the hotel in the city where they trained, just east of Tokyo.
The Olympics, postponed for a year due to coronavirus, open on July 23 and the gymnastics competitions start on July 24. The women's qualifying rounds begin July 25.