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The Chicago Bears were bracing for an injury to Jay Cutler long before the season started.

Now, they'll see just how prepared they are.

Cutler will miss Monday's game at San Francisco because of a concussion, leaving the Bears without their starting quarterback. The team announced the decision Friday, meaning Jason Campbell is the likely starter against the 49ers.

Star receiver Brandon Marshall said Cutler is getting better, but he also said there's a bigger picture that goes beyond this week's game.

"Our life, our health, is more important than football," Marshall said. "I think we'll get Jay back sooner than later."

For now, the Bears believe they have enough to get by. They brought in Campbell in the offseason for a situation like this, and he found out before Thursday's practice that he'll be starting.

"You definitely don't want to see anyone get hurt or injured in this business," said Campbell, who's made 70 starts in his career with Washington and Oakland. "We understand it is a tough sport. Sometimes, things like that happen."

Cutler's status was in question after he sat out the second half of Sunday night's loss to Houston. The Bears believe he was injured on a helmet-to-helmet hit by the Texans' Tim Dobbins, who was fined $30,000 by the league, late in the second quarter.

Cutler initially did not show any symptoms and took seven more snaps in the first half. It wasn't until halftime that the symptoms showed up, and the Bears went the rest of the way with Campbell. They also signed veteran Josh McCown this week, giving them a backup behind Campbell.

The 49ers, meanwhile, could be without starting quarterback Alex Smith, who suffered a concussion of his own last week. He practiced in a non-contact black jersey Wednesday and Thursday and hopes to be ready to play against Chicago.

The concussion isn't the first for Cutler. He missed a game after being sacked nine times in the first half of a loss at the New York Giants in October 2010. Last year, Cutler broke his right thumb late in a win over San Diego that put Chicago at 7-3. His replacement, Caleb Hanie, struggled and the Bears lost five of their last six.

That cost general manager Jerry Angelo his job. Phil Emery replaced him and retooled the roster, landing Marshall in a blockbuster trade with Miami and addressing several other areas — including backup quarterback by signing Campbell to a one-year deal.

"He's the next guy up and he's more than capable," Marshall said. "I think when you look at what happened to the Bears last year, I think that's the reason why he's here. He's more than capable and we're fortunate to have a starting quarterback as our backup."

That's why the Bears believe they can get by without Cutler, at least for now. They have an experienced backup and don't expect the same sort of meltdown.

"I understand a year ago what happened, but at the same time, I've got to do what I've got to do within the system, different football team," Campbell said.

The Bears are 7-2, one of the top records in the NFC. But they are in the tightest division in the league, with Green Bay at 6-3, the Vikings at 6-4 and Detroit still in the picture at 4-5.

Campbell, who threw for 94 yards last week, started six games for Oakland a year ago before breaking his collarbone. He has completed more than 60 percent of his attempts and thrown for 14,511 yards since he entered the league in 2005.

He's more of a pocket passer and isn't quite as mobile as Cutler, which led to this observation from Marshall.

"It's the opposite, you would think Campbell would be like Vick," he said. "But Jay Cut is like (Michael) Vick, and Jason is more of a pocket guy, I would say. Cut likes to run around a little bit, so that's a little opposite. But because of the picture we paint on black quarterbacks, it's supposed to be a guy who runs around a lot, but Jason does a good job in the pocket, really reading coverage, really taking control of the offense. We're fortunate to have him."

Until this week, Campbell hadn't worked with the starters in practice since training camp.

How fast he can get on the same page with the rest of the starters remains to be seen, even if the players don't expect any problems there.

In particular, it'll be interesting to see how the dynamic between the star receiver and the quarterback changes. Marshall has a long history with Cutler from their days in Denver, but it'll be Campbell throwing to him on Monday night.

"I can't make up for four years that they've been together," Campbell said. "But at the same time, you can see that on the field, when they play together, they see certain things together. A lot of that comes from the experience that they have from back in their days in Denver. But for me, just talking to B, we'll pretty much do what we do. At the same time, if we see things, then we see things. But we're not going to be trying to push the envelope on things that are just not there."