"Obviously we are going to lose one of our better pass-rushers [with McClellin likely out]," defensive end Julius Peppers said. "Hopefully he won't be out too long and will be back soon."
The Bears officially listed McClellin as having limited participation Thursday, and the starting defensive end did not practice Friday.
McClellin was named NFC Defensive Player of the Week on Tuesday for his performance against the Green Bay Packers, when he recorded three sacks and two tackles for losses in the Bears' 27-20 victory. McClellin had the hit the knocked Packers quarterback Aaron Rodgers out of the game with a fractured collarbone.
"No. 1, I feel bad on a personal level for him if he doesn't play because he really had a good game last week, we all know that," Bears coach Marc Trestman said. "He was moving in the right direction. I'm certainly disappointed for him.
"We need to find a way to do it with the guys that we have [healthy at defensive end]. That'll be David Bass, and Cheta [Ozougwu] will probably be [active], and we'll go from there."
Bass, an undrafted rookie out of Missouri Western State, has six tackles and 1.5 tackles for losses in four games this season. The Bears claimed Bass off waivers after the Oakland Raiders released him at the end of the preseason.
"If I'm blessed with the opportunity to have a bigger responsibility and a bigger role, then I need to embrace that, take it on and do my job," Bass said. "I just need to make sure I execute my assignments and give maximum effort."
Bass was credited with a season-high three tackles in the win at Lambeau Field.
"Bass is getting better," Peppers said. "We've been getting him in there so he can get some reps as we try to develop him. But he's coming along. We're going to need him to play this week, and he's one of the young guys we are counting on. We are going to need him."
Said Trestman: "I think Bass has athletic ability. He's strong up top and can move around. We've worked hard to develop him and we think he has some upside. He's certainly going to get an opportunity to play if this thing goes the way we think it's going to."
In order for Ozougwu to play on Sunday, the Bears would need to elevate him from the practice squad to the active roster. Ozougwu played in two games for the Bears in 2012 and contributed three tackles and one tackle for a loss. Another option to help ease the likely loss of McClellin is rookie sixth-round pick Cornelius Washington, who is on the 53-man roster. Washington has been active three times this season but appeared in only one game.
Meantime, quarterback Jay Cutler (groin) practiced without restrictions again Friday and is officially listed as probable for Sunday. The Bears (5-3) announced on Thursday that Cutler is expected to start against the Lions (5-3).