Jack Miller is facing a race against time to be fit for the Australian MotoGP, as he continues to pay the price for a high-speed crash.

The Queenslander broke his hand and three vertebrae on August 14 during a warm- up session at the Red Bull Ring in Austria, missing that race and the following Czech Grand Prix.

He pushed on to finish 16th at the Silverstone British GP but withdrew from last week's round at Misano.

Miller's team Marc VDS have ruled him out of this weekend's Aragon GP to give him time to recover properly from the injuries before next month's three flyaway rounds - in Japan, Phillip Island and Malaysia.

The 21-year-old said his hand was the main issue, but his back was still causing pain.

"Not riding 100 per cent fit with all of the injuries I've got at the moment seems like an unnecessary risk," he told the Australian Grand Prix Corporation's official podcast.

"We're not fighting for the championship - we're always fighting to be at the front but, if you're not 100 per cent fit, it adds another element of danger into an already dangerous sport.

"We decided to sit out (at Aragon) to try to be as ready as possible by the time I get to Phillip Island for my home race. It's one of my favourite tracks and somewhere I believe we can be really good at."

Miller will be replaced by former MotoGP world champion and current world superbike frontrunner Nicky Hayden.

"Obviously, we'd have preferred Jack to be racing in Aragon, but it's the racing that is stopping the two fractures in his hand healing properly," said team principal Michael Bartholemy.

"It makes sense to have him sit out this race in a bid to recover ahead of the three overseas races, one of which is his home race in Australia."

Hayden, 35, wished Miller a speedy recovery.

"He is a buddy of mine and he is a rider I believe in a lot, so I hope he can get healthy as quickly as possible to show the high potential we all know he has got," America's 2006 title winner said.

"He just needs to get his body right so he can perform."