"He's probably going to be down for a little bit. I don't know how long ... at his position, that's not an easy thing to deal with, so we'll just take it as it comes, but I think there's a chance we won't have him for a little bit," Campbell said.
Montgomery was injured at 7:34 in the second quarter Sunday in Detroit's 20-6 victory over the Buccaneers, after catching a short pass to the left side from quarterback Jared Goff. He lay on the field for a moment before ultimately walking off on his own. He was later ruled out for the rest of the game.
The Lions (5-1) were already playing without rookie running back Jahmyr Gibbs, who has missed the past two weeks with a hamstring injury. Campbell said Monday that he feels "a lot better" about Gibbs playing this Sunday against at the Ravens.
Montgomery had six rushes for 14 yards against a stingy Buccaneers defense. The Lions as a team finished with 40 rushing yards, their fewest in a win since 2016 against the Jaguars.
In Week 2, Montgomery suffered a thigh injury that forced him to miss the Lions' victory over the Falcons the next week. With 385 yards and six touchdowns, he is Detroit's leading rusher.
ESPN's Eric Woodyard contributed to this report.