MINNEAPOLIS -- Dalvin Cook had picked up another first down, with Minnesota clinging to a one-point lead over Detroit midway through the third quarter, when he planted his left leg on the turf with a juke to try to cut right for more yards.
His knee buckled , and the ball came loose.
The Lions recovered, and the Vikings never did.
Cook, the versatile, elusive and powerful running back who has helped energize an offense that often lacked potency last season, has likely had a promising rookie season cut painfully short.
Vikings coach Mike Zimmer said after the 14-7 defeat by the Lions that the team was concerned about Cook's anterior cruciate ligament, which if torn would put him on a rehabilitation program until next summer.
"We all said a prayer for him and hoped for the best," quarterback Case Keenum said.
Cook was scheduled for an MRI to determine the extent of the damage, but he was on crutches afterward with a bulky brace on the knee.
"I told him he's not the first great running back to have an ACL, if it is one, and come back pretty good," Zimmer said. "Dalvin will have a great career."
Cook's predecessor in the Vikings backfield, of course, was one of those ACL reconstruction success stories.
Adrian Peterson tore his in the second-to-last game of the 2011 season, only to return to action in less than nine months and rush for 2,097 yards in 2012 on his way to the NFL MVP award.
Cook was on his way to another standout performance, having scored on a 5-yard cruise into the end zone without being touched with 1:07 left in the second quarter.
He launched his "Chef Cook" celebration, pretending to hold a large pot while teammates Stefon Diggs and Adam Thielen pantomimed pouring ingredients in before Cook acted as if he were stirring them together.
A little later, the Vikings weren't having nearly as much fun. Such is the nature of this injury-influenced sport.
For now, Latavius Murray will fill in as the featured runner. He has more experience, but not the same burst, vision or pass-catching ability as the second-round draft pick from Florida State. Cook, who entered the week ranked second in the league in rushing, has 354 yards on 74 carries and two touchdowns. He has 11 catches for 90 yards as well.
"Dalvin's a really explosive player, and he has such good big-play ability," Zimmer said. "So we'll have to look at things differently. But if you lose a guy like him, you lose a lot of firepower."
The Vikings acknowledging losing some emotional steam, too. The rest of their possessions went punt, missed field goal, punt, turnover on downs and lost fumble, though there were myriad other reasons for the loss beyond the absence of Cook for the final 25:25 of the game.
"You never want to see one of our guys go down like that," defensive end Everson Griffen said. "He started off tremendous, so we hope everything works out for him in the best. But in this league it's next guy up."
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