Multiple members of Australia's track and field team were placed in isolation on the eve of the Tokyo Olympics athletics competition on Thursday after US pole vaulter Sam Kendricks tested positive for coronavirus.
Athletics Australia said members of the team were isolating after US chiefs confirmed two-time world champion Kendricks was out of the Tokyo Games after a positive Covid-19 test.
"Members of Australia's track and field team at the Tokyo Olympic Games are isolating in their rooms as a precautionary measure following news of a Covid-positive finding with a member of the US track and field team," Athletics Australia said in statement.
US swimming star Caeleb Dressel Photo: GETTY IMAGES NORTH AMERICA / Maddie Meyer
"Members of the Australian track and field team are now undergoing testing procedures in line with Australian Olympic team protocols."
The statement did not say how many athletes were involved but the Sydney Morning Herald reported the entire 63-strong track and field team had been told to isolate.
Kendricks earlier became the latest high-profile withdrawal from the Olympics after testing positive for coronavirus.
"We are saddened to confirm that Sam Kendricks tested positive for Covid-19 and will not compete in the Olympic Games Tokyo 2020," the United States Olympic and Paralympic Committee said on Twitter.
Japan's Hideki Matsuyama launches his bid for Olympic glory Photo: AFP / Kazuhiro NOGI
Organisers announced a daily record of 24 new Games-related cases on Thursday, three of whom are athletes, taking the overall number of positive cases to 193.
The figures do not include all cases at airports and in training camps.
Novak Djokovic is taking on Kei Nishikori in the quarter-finals of the tennis tournament at the Tokyo Olympics Photo: AFP / Giuseppe CACACE
In Olympics action, US swim star Caeleb Dressel notched his second triumph of the Games to stay on track for a potential six golds.
Dressel arrived at the Olympics tipped to push for a Michael Phelps-style medal haul and already has two wins under his belt, with a potential four to come.
The 24-year-old powered to the wall in the men's 100m freestyle in a new Olympic record time of 47.02sec to dethrone Australia's Kyle Chalmers.
Dressel, who spearheaded the United States to the 4x100m relay title earlier this week, will also race the 50m freestyle and 100m butterfly and could feature in two other relays.
Japan's Hideki Matsuyama launches his bid for Olympic glory Photo: AFP / Kazuhiro NOGI
The swimmer, who won two relay golds in Rio, said he was proud to claim his first individual title.
"I didn't want to admit it but now I did it I can admit it, it's a lot different," he said.
"You can't rely on anyone else. It's just you in the water, there's no one there to bail you out. It's tough. It's really tough. So I'm happy to actually do it."
Dressel's 13 world titles have prompted inevitable comparisons with Phelps -- winner of eight Olympic golds at the 2008 Beijing Games and 23 in total.
Only Phelps, Mark Spitz and Kristin Otto have won six or more golds at a single Olympic Games in swimming.
Robert Finke won another gold for the United States in the men's 800m freestyle while Australia's Zac Stubblety-Cook claimed the men's 200m breaststroke gold in a new Olympic record time of 2:06.38.
China's Zhang Yufei took gold in the women's 200m butterfly and China rounded off the morning session by smashing the world record in the 4x200m women's freestyle relay, finishing ahead of the United States and Australia.
The Olympic golf tournament has also lost stars to coronavirus but started at Kasumisageki Country Club with a number of top players still involved.
Austria's Sepp Straka carded a 63 to set the early pace before lightning forced the suspension of play.
The women's all-around gymnastics event is due to take place on Thursday evening without Simone Biles, who arrived seeking to equal or even better Soviet gymnast Larisa Latynina's career haul of nine Olympic titles.
Biles's decision to ditch a second event due to mental health concerns, hot on the heels of her dramatic withdrawal from Tuesday's team event, has raised serious doubts about the American superstar's further participation in the Games.
"The outpouring love & support I've received has made me realise I'm more than my accomplishments and gymnastics which I never truly believed before," the 24-year-old tweeted on Thursday.
Ten Nigerian athletes were among 18 competitors from "high-risk" nations barred from competing after failing to meet minimum standards for out-of-competition drug testing.
World Athletics' independent anti-doping arm said the athletes had failed to comply with rules that require athletes from countries deemed to be at highest risk of doping to undergo three no-notice out-of-competition tests in a 10-month period.
