When the Bears visit the Steelers Monday night in Pittsburgh, outside linebacker Khalil Mack will miss his second consecutive game with a foot injury.

The six-time Pro Bowler was ruled out of the contest Saturday after being unable to practice all week. After sustaining the injury Sept. 25 against Cleveland, Mack played in the next four games—recording three sacks—despite being either limited or held out of practice entirely.

Coach Matt Nagy lauded defensive coordinator Sean Desai and his assistants for being able to decipher how opponents try to attack the Bears defense with and without Mack on the field. 

"The biggest thing is just the next guy stepping up and having opportunities," Nagy said. "And then our coaches have to be able to make sure that understanding that from the other side, offensively, how they want to try to attack us, or who's the next guy that they want to either run to or run away from, and then we've got to have a counter for that."

Three other Bears have been ruled out of Monday night's game: Quarterback Nick Foles (illness), running back Damien Williams (knee) and tight end J.P. Holtz (concussion).

It appears the Bears defense will also line up without safety Eddie Jackson, who's listed as doubtful with a hamstring injury he suffered last Sunday on the second play from scrimmage against the 49ers.

Jackson, a 2017 fourth-round draft pick from Alabama, has started 70 of a possible 72 games in five seasons with the Bears, missing only the final two contests in 2018 with an ankle injury.

Two Bears are listed as questionable: Linebacker Alec Ogletree (ankle), who did not practice Saturday; and receiver Darnell Mooney (groin), who was limited.

There is some good news on the injury front regarding running back David Montgomery, who has missed the last four games after hurting his knee Oct. 3 against the Lions.

After returning to practice Thursday, Montgomery was activated off injured reserve Monday and will play against the Steelers.

"Beginning of [last] week, we wanted to see, 'How's he going to look?' You have no idea when he gets out there," Nagy said Saturday. "I think for all intents and purposes, he's looked really good."

For the Steelers, tight end Eric Ebron (hamstring) has been ruled out of Monday night's game and backup offensive lineman B.J. Finney (back) is questionable.