Adrian Peterson (ankle) leaves field on cart

Bad news from the Metrodome, where Minnesota Vikings tailback Adrian Peterson has suffered what appeared to be a significant left ankle injury after a run against the Oakland Raiders. Peterson hobbled to the sideline but just left the field on a cart.

Peterson has been dealing with an ankle injury this year but replays showed his ankle getting bent backwards in this instance. Peterson, whose 12-yard scoring run is the only touchdown of the game so far, has been a highly durable player in his career, missing just three games in five seasons. We'll keep you posted.

Toby Gerhart, who entered this week with 17 carries on the season, is the Vikings' backup running back.