Ravens defensive lineman Nnamdi Madubuike, the team’s top pass rusher, will miss Monday’s game against the Detroit Lions as he undergoes further testing for a neck injury, coach John Harbaugh said Saturday.

Madubuike, who’s never missed a game over five-plus NFL seasons because of injury, was sidelined for all three practices this week. Harbaugh said Madubuike showed symptoms after the Ravens’ win Sunday over the Cleveland Browns.

“They’re going to try to get to the bottom of it,” Harbaugh said. He declined to comment further or to speculate on whether the team could place Madubuike on injured reserve, which would sideline him for at least four games.

The Ravens (1-1) will be without three other starters against Detroit (1-1). Fullback Patrick Ricard (calf), tight end Isaiah Likely (foot) and outside linebacker Kyle Van Noy (hamstring) were also ruled out Saturday. Van Noy led the team with 12.5 sacks last season.

It’s unclear how Madubuike hurt his neck. He played 43 defensive snaps Sunday against Cleveland and was on the field until midway through the fourth quarter. He also spoke to reporters after the game.

Madubuike, a Pro Bowl selection each of the past two years, leads the Ravens with two sacks and 10 quarterback pressures this season, according to Pro Football Focus. His absence could loom large against Detroit’s rebuilt interior offensive line, one of the Lions’ few weaknesses on offense. Defensive linemen Travis Jones, Aeneas Peebles, Broderick Washington and John Jenkins have combined for seven pressures and no sacks in two games.

“It would hurt any team,” Peebles said of Madubuike’s absence. “He’s one of the best defensive tackles in this whole entire league. I love watching his game and I love studying his game, so it hurts not having an All-Pro defender out there, but it kind of is what it is.”

Practice squad defensive lineman Brent Urban could be elevated to help replace Madubuike’s run defense, while Peebles will likely take on more pass-rushing reps. The rookie was one of the most disruptive interior pass rushers in the Football Bowl Subdivision last year at Virginia Tech and impressed in the preseason.

“I know he’s going to play hard and he’s going to get after it, and I’ve got a feeling he’ll make a few plays,” Harbaugh said.

Likely was a limited participant in practice throughout the week, but he acknowledged Friday that, while he wanted to play Monday, he was mindful of the “long game.” Foot surgery wiped out most of Likely’s training camp and sidelined him for the Ravens’ first two games.

“They’re not rushing me back,” Likely said. “Me limited isn’t helping anybody. You guys want to see me be me.”

Van Noy left Sunday’s win in the second quarter and did not practice this week. Ricard, meanwhile, will miss his third straight game. Harbaugh said Monday that he’s “week-to-week” with a calf injury that has kept him from practicing for more than a month.

Note: Harbaugh indicated Saturday that running back Keaton Mitchell would not make his season debut Monday. Rasheen Ali, who left Week 2 with a concussion and has earned snaps as the team’s third-string running back ahead of Mitchell, was a full participant in practice Saturday. Mitchell “would help us on offense. We just don’t have the spot right now,” Harbaugh said. … The NFL fined Van Noy $17,389 for a “body weight” hit on Browns quarterback Joe Flacco on Cleveland’s first drop-back Sunday. Van Noy was not penalized on the play.

This article has been updated.