Cook was injured on the first play of Minnesota's opening drive in the second half of last Sunday's loss to the Seattle Seahawks. He did not practice Wednesday through Friday and will have two weeks to rest with the Vikings' upcoming bye in Week 7.
"Initially I thought I was cramping for a minute because it's in a weird spot," Cook said of his injury. "Went to the locker room and did some tests, and the only thing that was to do was to give it a go. That was all my call. I told them I had to go out there and try to see if I can go. I went out there and it was just a thing where I wasn't in game-ready, game-situation to play. I couldn't go out there and play a football game and be me. I knew we had some guys who could step up and play."
Alexander Mattison, the backup who rushed for a career-high 112 yards in Cook's absence, including 99 in the second half at Seattle, is set to start at running back for the Vikings. While he filled in for Cook in various capacities during his rookie season in 2019, Sunday will be the first start of Mattison's NFL career.
"I guess the best compliment I can give Matt is that when Dalvin leaves the game, I don't change my mindset at all," offensive coordinator Gary Kubiak said. "I mean he's a fine, young player, is playing behind a very established player in this league, so he's got a great example in front of him. Matt is a three-down player. He understands pass protections, catches the ball really well, and you guys have seen what he can do, so we're really proud of how he played the other night. I would say everybody expects it from him, because of watching him work, watching him practice and his preparation as a player, and [Kennedy Polamalu] does a really good job with him, so Matt has got a very bright future."
Cook, who signed a five-year, $63 million extension with the Vikings before the season, leads the NFL with 489 rushing yards and also has a rushing touchdown in each of the Vikings five games, bringing his total to 16 rushing TDs in his last 19 games.
The Vikings will also be without starting right guard Dru Samia, who showed up on the injury report on Thursday with a wrist injury and did not practice during the final two days of the week.
Coach Mike Zimmer declined to address how Samia got hurt or who would be starting in his place at right guard. Kubiak said this week that rookie offensive lineman Ezra Cleveland, who has been working at both guard and tackle, is "putting himself in position that he deserves opportunities" and that "his time is coming."
Cleveland, who the Vikings drafted 58th overall after three seasons playing left tackle at Boise State, spent training camp working at left guard. It remains unclear whether he'll play there if he's set to start, which means Minnesota would need to move Dakota Dozier to right guard.