The Australian Grand Prix has been officially postponed until November, with Imola returning in April as part of a revised 2021 F1 calendar.
Due to Covid-19 issues surrounding the race at Melbourne's Albert Park, the event will now take place on November 18-21.
The Chinese GP has also been provisionally been put on hold, which means a return to the schedule for Imola after it made a comeback in a heavily-revised calendar last year.
Via a statement, F1 said: "Formula 1 can today confirm that the 2021 FIA Formula One World Championship will open its season in Bahrain between 26th-28th March.
"The ongoing situation regarding COVID-19 has meant it is not feasible to begin the season in Melbourne, but the good news is that the Australian Grand Prix will now take place from the 18th – 21st November following an agreement between Formula 1 and the Australian authorities that shows the importance of the race in Australia to Formula 1 and our partners in Melbourne.
"Due to the ongoing travel restrictions in place, the 2021 Chinese Grand Prix will not take place on its planned date.
"Discussions with the promoter and authorities in China are ongoing with the potential to reschedule the race later in the season if possible.
"With the scheduled date not being feasible for China, Imola will return to the Formula 1 calendar on the revised date of 18th April.
"The TBC race in the calendar will be announced in due course and will take place on the new date of 2nd May. All revisions are subject to World Motor Sport Council approval.
"As a result of these changes, the number of races for 2021 will remain at 23 which is the largest ever Formula 1 calendar and we look forward to delivering this season through close collaboration with all our promoters.
"The season will start a week later than planned and end a week later with our season finale in Abu Dhabi.
"As stated previously, we expect fans to return to the grandstands and our exclusive Paddock Club for the 2021 season.
"We will continue to work closely with our promoters and partners to monitor the
ongoing COVID-19 situation and look forward to the start of the season in March."
Rescheduled 2021 F1 calendar
March 28: Bahrain
April 18: Emilia Romagna
May 2: TBC
May 9: Spain
May 23: Monaco
June 6: Azerbaijan
June 13: Canada
June 27: France
July 4: Austria
July 18: Britain
August 1: Hungary
August 29: Belgium
September 5: Netherlands
September 12: Italy
September 26: Russia
October 3: Singapore
October 10: Japan
October 24: U.S.
October 31: Mexico
November 7: Brazil
November 21: Australia
December 5: Saudi Arabia
December 12: Abu Dhabi
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