The Tokyo Olympics appears to be creeping towards a postponement, an unprecedented and costly exercise that involves ripping up years of planning.
As International Olympic Committee president Thomas Bach told Germany's SWR: "Postponing the Olympic Games is not like moving a football game to next Saturday."
Here are just some of the challenges:
As specialist website Inside the Games put it, the Olympics "gravitate around... a four-year cycle. If you wake up and the sun is in a completely different place, there are going to be consequences".
Much depends on the length of any postponement but shoehorning an Olympics into what is already a packed sporting calendar in 2021, for example, will be a logistical nightmare for both athletes, administrators and broadcasters.
One potential clash is the World Athletics Championships, currently scheduled for August 2021 in the United States -- a lucrative pay-day for athletes and TV networks.
Swimming is also scheduled to hold its World Championships in Japan from July 16 to August 1, 2021.
Adding to the crowded schedule is football's European Championships, already postponed from 2020 to 2021.
Olympic legend Carl Lewis has put the case for holding the Summer Games in 2022 alongside that year's Winter Games in Beijing, creating a "celebratory Olympic year".
There are 43 Olympic sites -- some temporary, some purpose-built, others repurposed for the Tokyo 2020 Games -- and all of them present difficulties in the event of a postponement.
The IOC highlighted this as one of the main concerns, warning: "A number of critical venues needed for the Games could potentially not be available anymore."
For example, one of the main selling points of the brand new 68,000-seater Olympic Stadium was that it would hold "cultural and sporting events" after the Games were over. Any such event would now need to be moved if it clashes with a rescheduled Games.
And it's not just sporting venues. Organizers have block-booked the enormous Tokyo Big Sight exhibition center to host the thousands of international journalists covering the Games.
This is one of Asia's premier venues for hosting large-scale conferences, and is booked many months in advance. Finding a suitable slot or persuading others to move could also be a challenge.
A major question mark hangs over the athletes' village, which occupies some prime real estate overlooking Tokyo Bay with a view of the city skyline and its famous Rainbow Bridge.
It will have 21 towers of between 14 and 18 floors with a total capacity of 18,000 beds during the Olympics and 8,000 for the Paralympics.
The plan was to renovate and convert the village into thousands of luxury condos, which are being sold off or put up for rent.
According to the website of the Harumi Flag developers, some 4,145 units were to be put up for sale. Viewings and sales of a first batch of 940 apartments began in summer 2019 and the vast majority have already been snapped up, according to Japanese media.
Postponement would mean delaying the renovation process and huge uncertainty for those who have already signed contracts -- including whether force majeure clauses would be triggered.
Among the "many, many" challenges the IOC mentioned, it highlighted that "the situations with millions of nights already booked in hotels is extremely difficult to handle".
In fact, one of the concerns before the coronavirus hit was a possible dearth of hotel rooms. One idea was to park a cruise ship offshore for emergency accommodation -- now surely a non-starter given the experience with cruise ships and the virus.
Hotel rooms have been block-booked in advance for many months. Many have paid a large deposit in advance and could face losing this, in addition to having to re-book quickly for a postponed date.
The hotel industry would also face huge uncertainty if the Games are delayed, adding to the headache already posed by a catastrophic drop in tourism.
Any silver linings?
A postponement by a few months to later in 2020 might solve what had previously been the biggest concern over the Tokyo Olympics: the sweltering heat of the Japanese summer.
It could even be conceivable to move the marathon back to Tokyo after it was shifted to the northern city of Sapporo amid fears over athletes' safety in the summer heat and humidity of the Japanese capital.
However, going ahead in the autumn would also put the Olympics in prime typhoon season -- as the Rugby World Cup found out to its cost last year.
A delay could also give sporting federations more time to prepare qualifying events, addressing one of the main concerns voiced by athletes.