Three-time Olympic champion had been preparing for mixed team gymnastics event in Tokyo on 8 November along with Russia's Nikita Nagornyy and Angelina Melnikova.
Two-time defending Olympic all-around champion, Uchimura Kohei has tested positive for COVID-19, and his status in the four-nation Friendship and Solidarity artistic gymnastics meet in Tokyo next month is now up in the air.
Uchimura will remain isolated in his room at the national training center and be monitored over the next six days. Negative COVID-19 tests on 4 and 5 November could allow the six-time World all-around champion to participate in the event, scheduled for 8 November.
"The test result came in today at around 16:30. He has a very normal temperature of 36.3 C. He is in a very stable condition,” International Gymnastics Federation president Morinari Watanabe told reporters during an online news conference on Thursday.
Watanabe, also an IOC member, explained that at present Uchimura is the only Japanese athlete to have tested positive and is currently asymptomatic. The Japanese team had been in quarantine since 21 October when all members first tested negative for the coronavirus.
"They took their first PCR test that day and all tested negative. But a second test on the 28th turned out positive for Uchimura," Watanabe continued.
"At this point, it's just Uchimura," he said. "If we find out it's spread through the rest of the team, at that point, they might pull out. All the other teams have been isolated in their countries."
Watanabe also said that the event would still be held even if Japan is forced to withdraw.
"It is an extremely disappointing result but we will continue to observe the situation," said Watanabe. I know Uchimura was looking forward to this event so we want to go ahead with it however we can - for him, especially.
"If we had to cancel because of him, it would be unbearable for him. We want to avoid that at all costs."
The 31-year-old Uchimura only returned to competition last month for the first time in a year, as a horizontal-bar specialist targeting the Tokyo 2020 Olympic Games in 2021. Next weekend's Friendship and Solidarity competition could be Uchimura's first international event since the 2018 World Championships in Doha.
Since those Worlds - where Uchimura was reduced to just four of the six apparatus - the Japanese star has struggled to find the form that's made him arguably the greatest male gymnast of all time.
In Uchimura's absence on the world stage, a pair of Russians, Artur Dalaloyan and Nikita Nagornyy, have emerged as stars of the sport, taking the 2018 and 2019 World titles, respectively. Both Dalaloyan and Nagornyy are expected to compete at the event in Tokyo for Russia, along with 2019 World all-around bronze medallist Angelina Melnikova.
2017 U.S. champion and World floor bronze medallist Yul Moldauer leads Team USA's contingent.