Formula 1 has confirmed the return of Imola to this year's schedule in the wake of the official postponements of the Australian and Chinese Grands Prix.
The sport's 23-race calendar is still a work in progress due to the lasting restrictions in many countries linked to the coronavirus pandemic.
Melbourne's inability to host F1's opening round means the season will kick off in Bahrain on March 28 and then head directly back to Europe, with the Emilia Romagna Grand Prix at Imola now slot in as the second race of the 2021 season.
Last year, the former home of the San Marino Grand Prix was added to F1's heavily revised schedule after a 14-year absence from the sport's calendar.
As a consequence of the latest permutations, the Australian Grand Prix has been moved to the back half of the season, to November 7 while China has yet to be assigned a date.
However, with Portimao expected to fill the May 2 slot vacated by Vietnam, Shanghai's return would imply a 24-race agenda, or an overboard roster of events that F1 teams likely will not accept.
Thus, an outright cancellation of the Chinese Grand Prix is the most probable outcome unless another race falls off the schedule.
“Due to the ongoing travel restrictions in place the 2021 Chinese Grand Prix will not take place on its planned date,” F1 said in a statement published on Tuesday.
“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 18 April.
“The TBC race in the calendar will be announced in due course and will take place on the new date of 2 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.”
Formula 1's revised 2021 calendar:
28 March - Bahrain GP
18 April - Emilia Romagna GP
2 May - TBC
9 May - Spanish GP
23 May - Monaco GP
6 June - Azerbaijan GP
13 June - Canadian GP
27 June - French GP
4 July - Austrian GP
18 July - British GP
1 August - Hungarian GP
29 August - Belgian GP
5 September - Dutch GP
12 September - Italian GP
26 September - Russian GP
3 October - Singapore GP
10 October - Japanese GP
24 October - United States GP
31 October - Mexico City GP
7 November - Sao Paulo GP
21 November - Australian GP
5 December - Saudi Arabia GP
12 December - Abu Dhabi GP