Formula One's Australian Grand Prix was postponed to November and China's race was put on hold indefinitely as the coronavirus forced a 2021 calendar re-jig on Tuesday.
The Australian race, usually the season-opener, was delayed from March to November, but no new date was set for the Chinese Grand Prix, normally held in April.
The announcement means a second season of coronavirus disruption for Formula One, which was delayed and truncated into 17 races in 'bubble' conditions last year.
The record, 23-race 2021 season will now begin in Bahrain on March 28, a week later than the originally scheduled start in Melbourne.
"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," F1 president Stefano Domenicali said in a statement.
Many of Formula One's teams are based in England where cases are surging, spurred by a more infectious new variant, further complicating matters.
Domenicali said talks were still underway about the Chinese Grand Prix. An F1 statement said the Shanghai race would be held "later in the season if possible", citing travel restrictions.
"Obviously, the virus situation remains fluid, but we have the experience from last season with all our partners and promoters to adapt accordingly and safely in 2021," Domenicali said.
Organisers said they also expected crowds to return to grandstands for the 2021 season after the action took place behind closed doors last year.
Italy's Imola race returns to the calendar in the Chinese slot on April 18, while the location of a race scheduled for May 2 was yet to be announced.
Australia's new slot is November 21, directly after races in the United States, Mexico and Brazil and before Saudi Arabia and the season finale in Abu Dhabi.
The Australian race was also called off last year, just hours before the season's first practice session, after a McLaren team member tested positive.
The pandemic eventually forced organisers to reduce the 2020 season from 22 to 17 events, all held in Europe, Russia, Turkey or the Gulf.
Despite the precautions Lewis Hamilton, who won a record-equalling seventh world title last year, was one of the drivers to test positive.
In Melbourne, construction around the temporary Albert Park street circuit never got underway and tickets did not go on sale, but organisers said the rescheduling will now allow the event to go ahead in November.
"As the third-last race of the season, this provides the opportunity to safely host what could be the championship-decider in Melbourne in the lead-in to summer," said Australian Grand Prix chairman Paul Little.
"We'd like to thank our loyal motorsport fans and employees for their understanding in these challenging times.
Australia's success in suppressing the virus has enabled it to host several major sporting events, including India's ongoing Test cricket tour and next month's Australian Open tennis in Melbourne.
But Australia's travel restrictions remain a major hurdle for organisers of the Grand Slam, with tennis stars set to undergo a mandatory 14-day quarantine period.
Melbourne, Australia | AFP