Minnesota Vikings running back Adrian Peterson tore a ligament in his left knee Saturday after taking a direct hit in a 33-26 win over the Washington Redskins.
An MRI showed the anterior cruciate ligament tear after the team returned to Minnesota.
Peterson said he knew "it was something bad" the moment he was hit and that he was in "severe pain" on he lay on the field. He was hurt when tackled by Redskins safety DeJon Gomes at the end of a 3-yard gain on the first offensive play of the second half.
"Anytime you take a blow to the knee like that, you're concerned about the ACL, MCL," Peterson said as he stood on crutches in the locker room. "I'm trying to stay as positive as I can."
The torn ACL would likely sideline Peterson for some nine months and make it difficult for him to return for the start of next season.
On the play after Peterson was hurt, Minnesota's Christian Ponder suffered a head injury when sacked by Adam Carriker and London Fletcher. Ponder remained in the game for one more play — a third-down incomplete pass — before heading to the locker room.
Coach Leslie Frazier said Ponder had "concussion-like symptoms." The coach said he's uncertain whether the quarterback will play in next week's season finale against the Chicago Bears.
"We'll have to weigh it when we get back," Frazier said, "and I'll follow the doctor's lead."
Peterson had 12 carries for 38 yards when he left. He also had a 1-yard touchdown run in the second quarter.
Ponder completed 8 of 13 passes for 68 yards. He was replaced by Joe Webb, who scored on a 9-yard run on the next series to give the Vikings the lead.
Joseph White can be reached at http://twitter.com/JGWhiteAP