Josh Grant crashed the Tuesday before the AMA Supercross season opener at Angel Stadium.
Grant, the winner of last year's season opener at Anaheim, did not get a chance to repeat. He qualified for the AMA Supercross main event, but pulled out at the last minute.
He hit his head, injured his shoulder and broke his nose while practicing at a private track near his home in Riverside.
The AMA Supercross season continues this weekend at Chase Field in Phoenix, Ariz., the second race of the season.