Adelaide Crows midfielder Brad Symes will miss the AFL pre-season after breaking his left thumb and right wrist in an incident after training.

Symes, 23, hitched a ride on the boot of car to return to the AAMI Stadium changerooms last Friday but slipped and fell when the vehicle negotiated a speed bump.

The club said on Tuesday he fractured the thumb on his left hand and broke the scaphoid bone on his right hand and with both arms in plaster, he would not be available to play for eight weeks.

That will rule him out of the NAB Cup and leaves him at risk of missing the opening round of the home and away season on March 28 because of a lack of match fitness.

Crows operations manager John Reid said if Symes had his time over he would not put himself in that position again.

"He's disappointed because he'd been training well, he's been one of our best performers," Reid said.

"That's eight weeks where he could have been playing and will now miss all the ballwork."

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