Extra strain

Athletes are arriving to find a restrictive environment, with daily testing, social distancing and no movement possible outside the Olympic "bubble". They are under orders to leave Japan 48 hours after their event.

In another example of the difficulties, Australia's entire athletics team was quarantined before departure after a member of their entourage returned an inconclusive test. The official later tested negative.

"We expect that there'll be cases associated with these Games and really what's going to matter is how we respond to that and to ensure that there's no complacency," said David Hughes, medical director of the Australian Olympic team.

Australia has 194 athletes in the Olympic Village backed by support staff including psychologists to help them deal with the "extra strain" of the anti-COVID measures.

Australian basketball star Liz Cambage was one of the athletes to pull out of the Games, citing mental health fears, while tennis player Nick Kyrgios withdrew due to the lack of fans.

Australian chef de mission Ian Chesterman said a "buoyant" mood in the camp was tempered by caution over possible mental health problems in the unusual environment.

"The mood and everything is sort of buoyant and excited to be here, and that we're conscious of the fact that it's like no other," he said.

"We have to make sure that athlete, mental health and wellbeing is at the forefront of all their thinking."

On Saturday, Games chief Seiko Hashimoto admitted athletes are "probably very worried" about coming to Japan, pledging full transparency over Covid cases.

Japanese and Olympic officials have also been forced onto the defensive over a welcoming reception for Bach attended by 40 people while Tokyo remains under a coronavirus state of emergency.