We're starting to get some reports on the severity of the knee injury Adrian Peterson suffered this afternoon against the Washington Redskins, and no matter how you slice it, it's pretty bad.

The Vikings' public relations office put out a tweet a few minutes ago that said that Peterson suffered a tear to the anterior cruciate ligament (ACL) in the knee, and that Coach Leslie Frazier would have more details in his press conference on Monday.

Tom Pelissero of 1500 ESPN in the Twin Cities is reporting that an "NFL source" has stated that Peterson not only tore his ACL, but also tore his medial collateral ligament (MCL) as well. Fortunately, neither source is reporting a tear of the posterior cruciate ligament (PCL), which means that Peterson did not hit the same "trifecta" that former Viking Daunte Culpepper reached when he got his knee injured in a 2005 game against the Carolina Panthers.

Still, with knee injuries being what they are, it makes you wonder if even an athlete of Adrian Peterson's abilities will be ready for the 2012 season and, if he is, what state he'll be in when he comes back.

But, for now, the diagnosis on Adrian Peterson's left knee appears to be at least a torn ACL, and possibly worse. We will keep you updated on any pending developments with this story.