There is "no guarantee" that Formula 1 will get through its full 23-race calendar in 2021, F1 CEO Stefano Domenicali has admitted.

The original 2021 calendar has already been tweaked, with the season now set to start in Bahrain - amid empty grandstands.

It is hoped that by the time the sport gets back to Europe, fans will be back at the circuits - including Monaco, where organisers are already erecting the grandstands.

"That is the great hope," Domenicali told Servus TV.

"The goal is of course to have fans on the track again, but we have to make sure the drivers and teams are protected. We also have to look at what the individual states specify.

"We have to be ready for the time when we can have spectators with us again. Thousands of fans will come back to the tracks when it is possible again," he predicted.

However, his first priority is simply to ensure that as full a season as possible takes place.

"First of all, we have to see that we can pull through the season at all. In such a pandemic, nothing can be taken for granted - there is no guarantee," said the Italian.

"The good thing is that we are starting now in Bahrain. I am here already, I've held some important meetings and I'm happy.

"Then we'll have to look at the next steps on a case-by-case basis, to see what the pandemic looks like. Hopefully with the vaccinations it will be better and we can look forward to a good future with the world championship.

"That is the top priority this year," Domenicali added. "There has been a lot of negative talk about this sport, but when you look at the audience numbers, we're talking about one of the greatest sports in the world.

"We have some interesting combinations this year and we can see that Red Bull Racing has taken a step. I hope for close racing," he said.