Martin out of Australian MotoGP with fracture

Title contender Jorge Martin was ruled out of Sunday's Australian MotoGP with a fractured arm, dealing a massive blow to his world championship hopes.

The Spanish Aprilia rider came off his bike at high-speed during Saturday's sprint race while challenging eventual winner Marc Marquez for the lead on lap eight, sliding through the gravel.

He was taken to the circuit medical centre following the crash with Aprilia saying he had been "declared unfit" to race on Sunday.

There were initial fears that he suffered two fractures of his forearm near the wrist and that Martin may have to return to Spain for surgery. But scans showed there was only one and it was "non-displaced", meaning the bone remains aligned.

"The only confirmed injury is a non-displaced fracture of the distal radius," the team said.

"Consequently, the rider will not be returning to Spain and will undergo the necessary treatment over the coming days."

There are four legs of the season left after Australia, with the Malaysian MotoGP next weekend.

Victory in the sprint for Ducati's Marquez put him 10 points clear of Martin in the standings ahead of the final MotoGP around the waterfront Phillip Island circuit on Sunday.

The race is in doubt with no track action so far due to rain and poor visibility.