Four Bears players missed practice Friday and were ruled out of Sunday's game in Tennessee: defensive tackle John Jenkins (ankle), center Sam Mustipher (knee), defensive end Roy Robertson-Harris (shoulder) and quarterback Mitchell Trubisky (right shoulder).

The Bears will be especially thin on their offensive line against the Titans, missing three regular starters. Left guard James Daniels (pectoral) and right tackle Bobby Massie (knee) are on injured reserve, and center Cody Whitehair is on the reserve/COVID-19 list.

Also unavailable are two top reserves in Mustipher and Jason Spriggs, who started in place of Massie at right tackle last Sunday against the Saints but has since been placed on the reserve/COVID-19 list.

The Bears' two healthy remaining offensive linemen are left tackle Charles Leno Jr. and right guard Germain Ifedi, who was activated Friday and returned to practice after spending four days on the reserve/COVID-19 list.

"Thankfully, I got called this morning and I was cleared to come in," Ifedi said. "I was able to get in a good practice today. I'm super excited. It's big, especially for an offensive lineman, a position that's all about timing and being in the right spots. It's tough to go a week off and do that."

Rashaad Coward, who has started the last three games at left guard in place of Daniels, practiced in full this week and was removed from the injury report after recovering from an ankle issue.

The only other offensive linemen currently on the Bears' 53-man roster are first-year pro Alex Bars and rookie seventh-round draft picks Arlington Hambright and Lachavious Simmons. Linemen on the practice squad are Dieter Eiselen, Aaron Neary and Badara Traore.

Regardless of who plays where Sunday, the Bears won't have the same experience on their offensive line as they normally do with their regular starters. They also had one fewer practice this week because Halas Hall was closed Thursday after a player tested positive for COVID-19.

As a result, coach Matt Nagy has simplified assignments to give the young players the best chance to succeed.

"We'll do everything we can to make sure that they can play fast," Nagy said. "Simplifying things and allowing them to play fast is something that we'll do. If there's something in there that's too much, then we can't do that.

"Not having practice yesterday, today was a long day for us because we had to catch up with some of our other stuff that we missed yesterday on the field. But they did a really good job, mentally, really in all three phases. We'll continue to simplify as much as we can so that we can play fast and play better."

Nagy is hoping that the untested linemen will make the most of a rare opportunity to play.

"I want to try to look at the positives in all of this," said the Bears coach. "None of us can promise anything, but man it would be really cool to see some of these younger guys step up and do well. Are they going to get beat at times? Yeah. In the run game and pass game, it's probably going to happen. But how do they respond to that? And then how do they respond to the coaching, etc. But this is what it's all about."

Trubisky, meanwhile, is out with a right-shoulder injury he suffered on his only snap in last Sunday's loss to the Saints when he was tackled by linebacker Alex Anzalone on a 3-yard run.

Nagy said that he doesn't anticipate Trubisky being placed on injured reserve and revealed that the injury is similar but not as severe as the one that sidelined him for two games in 2018.

"As far as where he's at mentally and sympathizing with him, this is a kid that's obviously been through a lot," Nagy said. "For one play, for him to come in and try to help the team and unfortunately have that happen, there's a lot of different ways you can look at it.

"I'm going to continue to go back to this and say this about Mitchell: He is a kid that does everything he possibly can and cares a lot about this game and about his teammates. For him, when you have somebody like that, you really, really care about him as a player and a person. And so, just for him to continue to stay positive, for us to help him stay positive and be there to support is all we can really do."

In other injury news, rookie tight end Cole Kmet is listed as questionable with a groin injury after being limited in practice Friday.

For the Titans, receiver Adam Humphries (concussion) and punter Brett Kern (wrist) have been ruled out of Sunday's game, while outside linebacker Jadeveon Clowney (knee) and cornerback Tye Smith (shoulder) are questionable.

Clowney is expected to be a game-time decision after being held out of practice all week.

"We're just trying to do what is best for him, and what's best for the football team, and that was to give him a couple of days of rest," Titans coach Mike Vrabel said Friday. "We'll see where he's at tomorrow and at 10:30 Sunday (when the inactives are due) make a decision on the 48 guys that go to the game."