The 2020 Olympic and Paralympic Games in Tokyo have been thrown into further doubt after Canada became the first major country to withdraw.
Japan's Prime Minister, Shinzo Abe, has admitted for the first time that the games could be postponed.
Australia's team has said it is "clear" the games cannot go ahead and told its athletes to prepare for 2021 games.
The International Olympic Committee (IOC) is expected to decide the fate of the games in four weeks' time.
The games are currently due to begin on 24 July.
What did Canada say?
The country's Olympic and Paralympic committee said it had taken "the difficult decision" to withdraw after consulting athletes, sports groups, and the Canadian government.
It then "urgently called" on the IOC, International Paralympic Committee and World Health Organization, to postpone the games for a year.
"While we recognize the inherent complexities around a postponement, nothing is more important than the health and safety of our athletes and the world community," their statement said.
The Canadians later posted a message on Twitter saying: "Postpone today. Conquer tomorrow."
What did Shinzo Abe say?
For weeks, Japanese officials have said the games will go ahead as planned.
But, speaking in parliament on Monday, Mr. Abe admitted for the first time that Tokyo 2020 might have to be delayed.
"If it is difficult to hold [the games] in a complete way, a decision of postponement would be unavoidable as we think the athletes' safety is paramount," he said.
But he insisted the games would not be canceled altogether.
The Olympics have never been postponed or canceled in peacetime. The 1940 Olympics - which were called off because of World War Two - were due to be held in Tokyo.
What is the International Olympic Committee's position?
The IOC has said the postponement is one "scenario" but insists that cancellation "would not solve any of the problems or help anybody".
In a letter to athletes, IOC president Thomas Bach said: "Human lives take precedence over everything, including the staging of the games...
"At the end of this dark tunnel we are all going through together, not knowing how long it is, the Olympic flame will be a light at the end of this tunnel."
What do other countries and athletes say?
On Monday, Australia told its athletes to prepare for an Olympics and Paralympics in the northern summer of 2021.
"It's clear the games can't be held in July," Australian chef-de-mission Ian Chesterman said.
On Sunday, the head of World Athletics, Sebastian Coe, wrote to Mr. Bach to say holding the games in July was "neither feasible nor desirable".
USA Track and Field has called for a postponement, as has the competitors' group Global Athlete.
"As the pandemic gets worse and worse and there are more and more societal restrictions put in place, I think the call needs to be made now," said British cyclist Callum Skinner, who fronts the Global Athlete.
DoubleTrusty Product Your Health
- Special 3 layer non-woven designed, provides protection against dust, air pollutant, and the droplet, etc
- Shipping within 48 hours
- DHL Fast Shipping in 7-10 days