MINNEAPOLIS _ Dalvin Cook made the cut and appeared to know instantly something wasn't right. Cook, who had 66 rushing yards Sunday, instantly grabbed at his left knee while dropping the ball on his 13th carry of the game.
The Vikings fear Cook suffered an injury to his left anterior cruciate ligament, according to head coach Mike Zimmer.
"We're concerned about his ACL but he's going to get an MRI in the morning and we'll find out," Zimmer said, adding: "If you lose a guy like him, you lose a lot of firepower."
The fumble eventually led to a Lions touchdown after Cook, their rookie star, went down. Cook immediately went to the locker room and was ruled out almost instantly by the Vikings medical staff.
Cook entered Sunday second in the league with 288 rushing yards.
