The Australian and Chinese Grands Prix have been postponed due to COVID-19 restrictions, Formula 1 has announced.
The 2021 season, which is due to take place over a record-setting 23 races, was set to begin at Albert Park in Australia on March 21.
However, the country has imposed a mandatory 14-day quarantine period for all overseas arrivals, meaning a Grand Prix would be unviable.
The race has instead been rescheduled, and is now set to take place between November 19-21.
That has resulted in the Brazilian Grand Prix being moved forward to November 7, whilst events at Abu Dhabi and Saudi Arabia will take place a week later than planned, on December 5 and 12 respectively.
The Chinese Grand Prix, meanwhile, has also been postponed as a result of strict quarantine measures in the country. Discussions are ongoing about a new date for the race.
Meanwhile, it has been announced that a race at Imola has been added to the calendar, with the circuit having hosted a Grand Prix last season for the first time since 2006 as part of a revised 17-race calendar.
Bahrain is now set to host the season opener, scheduled for March 28, with Imola hosting the second race of the season on April 18.
There is still one slot yet to be filled on the calendar following the cancellation of the Vietnam Grand Prix, which had been due to make its F1 debut this season. The identity of that Grand Prix is yet to be confirmed.
Despite the postponements, Formula 1 president Stefano Domenicali has confirmed that the sport will complete the planned 23 races.
He explained: “We are pleased to confirm that the number of races planned for the season remains unchanged.
“The global pandemic has not yet allowed life to return to normal, but we showed in 2020 that we can race safely as the first international sport to return and we have the experience and plans in place to deliver on our season.
“It is great news that we have already been able to agree a rescheduled date for the Australian Grand Prix in November and are continuing to work with our Chinese colleagues to find a solution to race there in 2021 if something changes.”