After weeks of hedging, the International Olympic Committee (IOC) took the unprecedented step of postponing the global extravaganza that's been cemented into the calendar for more than a century.

The Tokyo Games, slated for 11,000 athletes from more than 200 countries and at a reported cost of $28 billion ($A47b), had been scheduled to start on July 24.

They will now be pushed into 2021 on dates to be determined.

They will still be called the 2020 Olympics - a symbolic gesture that IOC chief Thomas Bach hopes will allow the games to "stand as a beacon of hope."

After a call between Japan's Prime Minister Shinzo Abe and Bach on Tuesday, the parties said the Games would be moved to next year to be a celebration of triumph over COVID-19.

"This Olympic flame will be the light at the end of this tunnel," Bach said.

An "unprecedented challenge for mankind" had inevitably led to an unprecedented challenge for the Games, he added.

Only World War I and World War II have forced the Olympics to be cancelled; in 1916, 1940 and 1944.

Now, a microscopic virus that is wreaking havoc with daily life around the planet, to say nothing of its sports schedule, has accomplished what no other virus (Zika in 2016), act of terrorism (the killing of Israelis in Munich in 1972), boycott (1980 and 1984) , threat of war (frequent) or even actual world war has managed to do: postpone the games and push them into an odd-numbered year.

Four-time Olympic hockey champion Hayley Wickenheiser, the first IOC member to criticise the body's long-held, dug-in refusal to change the dates, called the postponement the "message athletes deserved to hear."

"To all the athletes: take a breath, regroup, take care of yourself and your families. Your time will come," she wrote on Twitter.

When will that time be?

Nobody knows yet.

It was a big part of the reason the IOC refused to announce a postponement that was becoming more inevitable with each passing day.

Another was finances as broadcasters and sponsors instead gear up for what they hope will be a party at the end of the struggles in 2021.

There are now numerous difficult changes the IOC leaders and Olympic organising committee have to make in the coming weeks and months - from arenas and stadium contracts, the budgets of the individual national Olympic committees and the availability of the 80,000 volunteers required.

There's also the matter of the international sports schedule with more than 30 sports on the Olympic program scheduled to have key events next year.

"Give us a bit of time to study all of these questions and to put this huge jigsaw puzzle together, then to have finally a successful Olympic Games in Tokyo 2020," Bach said.

But the most difficult decision has been made.

So, onto 2021.

As far as the Olympic community - and perhaps the world at large - is concerned, it can't get here soon enough.