Every Minnesota Vikings fans’ worst nightmare was just realized. Adrian Peterson went down with an ugly leg injury and it appears as though his 2011 season is over.This is the worst case scenario for a Vikings team that has nothing left to hope for this season and can ill afford to have their best player sustain a devastating injury in a meaningless game.UPDATE: Saturday, December 24th at 6:22 p.m. ESTThe Vikings may be saying that AP has a sprain, but Fox Sports’ Jay Glazer is hearing from three different sources that the initial belief is that Peterson tore his ACL. UPDATE: Saturday, December 24th at 4:48 p.m. ESTAccording to the Pioneer Press, Minnesota Vikings head coach Leslie Frazer has announced that Adrian Peterson has a sprained knee. Update: Saturday, December 24th at 3:21 p.m. EST CBS Sports Tweeted out an article that states that Peterson and Christian Ponder are both out of the remainder of this game. Given the nature of this injury, the Vikings will be lucky if he’s ready to go next week.Fantasy ImpactIt’s championship time in fantasy football and those who got to this point on the back of Peterson are losing him at the most critical time imaginable.It’s looking like the star back is done for at least the day and this could be the difference between winning it all and being left in the cold. Who’s the Backup?Toby Gerhart is a solid backup. He’s not Peterson by any means, but he’s a guy who can do it all and has proven he can carry the load. While the drop-off between Peterson and Gerhart is significant, Gerhart is capable enough to keep the Vikings’ offense from collapsing with AP in the locker room.The problem is that even with the best back in the league, the Vikings have had trouble winning. With Gerhart in the lineup, their struggles will only get worse. Devastation Scale: 10/10The Vikings have no playoff shot, a decent backup back and there is no word on how bad Peterson’s injury is.Christian Ponder just went down with a concussion and the decimated team is running out of things to be thankful for this Christmas Eve. Timeline for ReturnThis was an ugly injury. It’s hard to imagine him seeing the lineup again this season and at this point, Vikings fans just need to hope that the effects of this injury aren’t felt long term. What They’re SayingESPN’s John Clayton speaks on the Vikings’ spell of injuries.