Minnesota Vikings' rookie running back Adrian Peterson will have an MRI exam today after injuring his right knee during Sunday's loss in Green Bay. Peterson, who set a National Football League record with 296 rushing yards in the Vikings' previous game, left in the third quarter yesterday after getting hit in the knee by Packers' cornerback Al Harris. Peterson, 22, told reporters afterwards that he's "banking it's a sprained knee." Peterson finished with 45 yards on 11 carries in the 34-0 loss, and the injury might hurt his chances to break Eric Dickerson's rookie and all-time records for rushing yards in a season. Peterson has 1,081 through nine games.