The Vikings' fears about Dalvin Cook's left knee were confirmed on Monday morning, when a MRI showed the rookie running back tore his anterior cruciate ligament in the third quarter of Sunday's game against the Detroit Lions. He will miss the remainder of the season.
Coach Mike Zimmer said Cook will have surgery once the swelling in his knee subsides, and added the running back has additional damage to his knee typically associated with torn ACLs.
"Like most of these ACLs, there's a little bit of cartilage; I think a meniscus," Zimmer said. "It's a normal, typical ACL."
Cook was injured with 10:35 left in the third quarter on Sunday, when his knee appeared to buckle as he made a cut on Lions safety Tavon Wilson at the end of a 10-yard run. Cook immediately grabbed his left knee as he went to the ground, fumbling the ball as Wilson hit him.
He was able to walk off the field with some assistance, and returned to the sideline at the end of the game with a sleeve on his knee, but had a brace on his left leg as he limped out of the locker room on crutches after the game.
"He's a great kid. I'm extremely impressed with what he's done to this point," Zimmer said. "It's obviously a terrible thing for him and for us but we'll move forward and go from there. But he's a great worker and I have no doubt that he'll come back from this."
Cook had run for 66 yards and a touchdown on 13 carries Sunday. His 354 yards in the first four games of his career were the second-most in Vikings history, behind only Adrian Peterson's 383.
It is Peterson's example that the rookie will now look to follow.
The running back's return from a torn ACL in 2012 -- just nine months after Peterson sustained the injury -- changed the landscape for what was possible from players returning from major surgery. Peterson ran for 2,097 yards that season, winning MVP honors while playing through a sports hernia he sustained in the second half of the season.
His recovery also helped shine the spotlight on the Vikings' athletic training staff, which directed Peterson's return and won praise for its ability to get injured players back to full strength quickly.