Six-time X Games gold medalist Levi LaVallee withdrew from X Games Aspen 2013 Sunday morning because he aggravated upper back and left triceps strains during practice.
LaVallee, who won gold medals in Freestyle and Speed & Style earlier in the games, had been scheduled to compete in SnoCross and Best Trick later Sunday.
"Super bummed to report this, but I tore a muscle in my back and after trying to ride SnoX practice I will not be able to continue on," LaVallee wrote on his Facebook page. "The Doc said if I push it, I could end up in a bad place. Thank you all for the amazing support that helped me bring home two gold medals!"
Alternate rider Dave Joanis will race in SnoCross later Sunday while the Best Trick competition will now be a field of seven competitors.
LaVallee now has nine X Games medals overall.