Sunday's MotoGP race in Australia was cancelled because of bad weather at Phillip Island.
The race, which would have been the final one at the legendary circuit off the coast of Melbourne, was delayed and then cancelled because of rain and poor visibility.
After cancelling the earlier Moto 2 and Moto 3 races, organisers tried to get the MotoGP race on by pushing it back several hours.
The track looked dry in some areas as the rain eased off.
But, ultimately, a lack of visibility meant that medical helicopters would be unable to fly over the circuit, which led to the decision to cancel the race.
Race director Graham Webb said: "The helicopter needs a window of around 60 minutes in both places - Phillip Island and Melbourne - in order for us to start the race.
"Just based on safety, we need to make sure that, if we do have any issues, we're covered, we can get a rider quickly to hospital.
"Most circuits, we can reach a circuit within 45 minutes, which is our regulation, but here in Phillip Island the hospital is further than 45 minutes by road and therefore we rely on the air ambulance."
Reigning champion Marc Marquez leads the standings by 10 points with four races left.
The Australian MotoGP is moving to a new street circuit in Adelaide from next season.
Other than two years lost to the coronavirus pandemic, Phillip Island has been a fixture on the world championship calendar for 30 years.
Australian two-time world champion Casey Stoner celebrated six wins in succession from 2007 to 2012, while compatriot Mick Doohan sealed his fifth and final world title with victory in the 1998 race.
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