LAKE FOREST, Ill. -- Jason Campbell will replace Jay Cutler as the Chicago Bears' starting quarterback on Monday night against the San Francisco 49ers, the team announced Friday.

Cutler suffered a concussion Sunday night on an illegal hit by Houston Texans linebacker Tim Dobbins. He did not immediately display the symptoms of a concussion after Dobbins' hit and stayed in the game for an additional seven plays before being ruled out at halftime. Dobbins was fined $30,000.

Bears rookie defensive end Shea McClellin, who also suffered a concussion Sunday, will be held out Monday night as well.

"It feels good to get back in there and play, but you never want to have the opportunity to play because of someone's injury. But we understand the position we play; those things occur sometimes," said Campbell, who said he was told he would start before Thursday's practice.

Campbell hasn't started a game since Oct. 16, 2011, when he suffered a broken collarbone with the Oakland Raiders.

"It's a tough opponent we have Monday night," Campbell said. "No one said it's going to be easy, but we have to go there and fight together and we have to play as a unit. You have to let it hang out in a game like this. We have all the respect in the world for the 49ers and what they do, especially on the defensive side of the ball. It's a big part of the reason why they were in the NFC Championship Game a year ago. Utmost respect. We understand it's going to take a total team effort."

Campbell is confident, but he's also realistic.

"Everyone knows if you haven't played in a while, you're not going to be like a Peyton Manning," he said. "You have to do what you do and do it to the best of your ability. Jay is good at what he does and I'm good for different reasons for things that I do. That's the way I have to play the game."

Cutler's chemistry with receiver Brandon Marshall, going back to their days with the Denver Broncos, has been one of the reasons the Bears are 7-2. But Marshall is confident the Bears can win with Campbell, who was brought in after the team collapsed last year after a Cutler injury. The Bears went from 7-3 with Cutler to finish 1-5 and out of the playoffs as Caleb Hanie struggled in a backup role.