The Vikings' fears about Dalvin Cook's left knee were confirmed 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 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 suffered 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.

"I talked to him last night about it, about the doctors who we have here and the medical staff, how they were able to rehab the last great runner here," Zimmer said. "I expect him to come back and be the same as he was."

In the short-term, however, the biggest thing the Vikings might miss about Cook is the number of big plays he made in such a short time. He was tied for second in the league with four runs of 20 yards or more — after the Vikings had only six all of last season — and posted another 36-yard gain on a reception.

"Dalvin had unbelievable big-play ability in a lot of different ways," Zimmer said. "We are going to have to continue to look for more ways to implement some big plays in the offense, probably."

With Cook out, the Vikings could turn to Latavius Murray, whom they'd signed to a three-year, $15 million deal in March. Murray missed the Vikings' offseason program, and much of training camp, while recovering from offseason ankle surgery, and has carried only 14 times for 38 yards in the Vikings' first four games.

He played 19 snaps Sunday to Jerick McKinnon's 10; Zimmer said he also expects McKinnon's role to increase, while adding the Vikings could look at adding another running back. Bronson Hill is the only healthy running back on the team's practice squad.

"We're looking at everything now," Zimmer said.

Murray said Monday his right ankle still doesn't feel completely normal after the surgery, which was done to clean up an injury he'd suffered in Oakland last year. But the running back said he's healthy enough for a big workload Monday night in Chicago if needed.

"It's not going to quite feel the same for a while," he said. "I knew that dealing with my previous ankle procedure [on his left ankle in 2013]. But for me, it's being well enough to be out there and help the team. I don't know when that day will come [that I feel 100 percent]. I feel good enough to be out there and be confident in myself, that I can play at a high level."