"I expect him to come back and be the same that he was," head coach Mike Zimmer said during a press conference.
The injury will end a promising season for Cook. The 22-year-old had established himself as one of the focal points of Minnesota's offense, rushing 74 times for 354 yards and two touchdowns and adding 11 catches for 90 yards. He was an early candidate for Rookie of the Year.
He suffered the non-contact injury in the third quarter on a run play up the middle of the field. As he attempted to make a cut to the right, his left knee gave out, and he immediately reached for it, fumbling the ball.
With Cook out for the season, the Vikings will turn to Latavius Murray in the backfield. The former Oakland Raider signed a three-year, $15 million deal with the Vikings this offseason. Murray rushed for 1,854 yards and 18 touchdowns between the 2015-16 seasons with Oakland.
Jerick McKinnon will play a larger role for the team in Cook's absence as well.