(CBS) In the preseason, teams aren’t focused on the outcome of the games. Rather, they’re focused on putting up zeros, as in no injuries. Neither the Bears nor the 49ers achieved this preseason goal, and Week 1 of the regular season was equally unkind.

The Bears are dealing with injuries to several starters on offense. Center Roberto Garza (right ankle) and left guard Matt Slauson (left ankle) are out, while wide receivers Brandon Marshall (right ankle) and Alshon Jeffery (right hamstring) are questionable and Josh Morgan (groin) is doubtful.

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The 49ers are dealing with injuries to two starters on defense, as cornerbacks Chris Culliver (concussion) and Tramaine Brock (toe) are questionable, and one on offense, as right tackle Anthony Davis (hamstring) is also questionable.

So, when these two teams meet to play Sunday night (7:30 p.m., NBC) in the first ever game played at Levi’s Stadium, it will be a test of which front office has fielded the deepest roster.

Both of these teams will look to play keep-away with their offenses for two reasons: to keep the opposing offense off the field and to protect their vulnerable defenses.

In 2013, the Bears’ run defense was historically bad, giving up league-high totals in rushing yards (2,583) and average yards per carry (5.3). Their deficiencies against the run carried over to Week 1, when the Buffalo Bills gashed them for 193 more.

Heading into a matchup against one of the league’s most innovative run schemes, this doesn’t bode well for a Bears defense that continues to struggle with assignments and gap control. The 49ers blend a power run scheme with one of the league’s most dynamic dual-threat quarterbacks, Colin Kaepernick, who has the Bears’ attention.

“No. 1, he is one of those mobile quarterbacks,” Chicago coach Marc Trestman said. “He’s an extremely explosive player, as explosive as they get in this league. He can not only throw well in the pocket, he can throw outside the pocket. And then it comes down to, obviously, keeping him in the pocket and making him throw from the pocket. That’s always the best way when a guy can run like that. You’ve got to keep mobile quarterbacks in the pocket.”

Since Kaepernick took over as their starter, the 49ers have perfected the zone-read play, a scheme that has given the Bears fits since the Seattle game back in 2012. Given their struggles to defend it, the Bears anticipate more of it this weekend and beyond, but Trestman expects his team to be assignment-sound.

“We’ve got to do a great job of doing our job on the read zone, it’s just that simple,” Trestman said.” “That when it comes up, everybody’s got to do their job no matter what that job is. Whether it’s stopping the run or having the quarterback or whoever it might be, that we’ve just got to lock in to the proper fits and doing exactly what our assignment is during that time. And that’s the most difficult part of it, is staying disciplined regardless of what your role is. Because sometimes it doesn’t look like it’s the best thing when you just look at that individual person, but they’re doing what they have to, to stop the play.”

Last week against the Cowboys, the 49ers used rookie Carlos Hyde on zone read plays, and he showed a lot of burst through the line, averaging 7.1 yards per carry.

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Kaepernick was efficient throwing the ball against Dallas as well, posting the fourth-highest quarterback rating of his career (125.5) and twice connecting with tight end Vernon Davis on touchdown passes.

The NFL is a no-mercy league, so it’s safe to assume the 49ers will pound away at the Bears defense to see how they hold up and build in some misdirection, bootlegs and play-action passes.

Offensively, the Bears will be dealing with new personnel in a hostile environment, which will make communication and continuity a challenge.

The Bears took note of the success the Cowboys had against the 49ers running outside-zone run plays. Given the injury situation and how the offense may be positioned from a personnel standpoint on Sunday night, quarterback Jay Cutler feels establishing the run will be crucial.

“With the way Matt (Forte) is playing, with the way our offensive line is blocking, kind of how we are set up offensively this week, the run is important to us this week,” Cutler said. “We’ve got to stay in rhythm, we’ve got to keep them honest and throw the ball down the field a little bit. But it’s (establishing the run) something we’ve definitely talked about and emphasized.

Despite the 49ers’ secondary being banged up, the Bears’ own injuries may prevent them from taking advantage. Furthermore, San Francisco defensive coordinator Vic Fangio throws in man/zone combination coverages that have given Cutler trouble in the past. Chicago offensive coordinator Aaron Kromer’s focus is on finding plays to beat specific coverages, rather than trying to scheme specific matchups.

“They do a good job of zone coverage although matching in some man situations within the zone, so it’s part-zone, part-man and they don’t show it pre-snap,” Kromer said. “They also do a good job of making you throw the ball underneath and go the long, hard way.”

Will Cutler be patient enough to take what the defense gives him? He’s struggled in situations like this in the past and against the 49ers in general, posting an 0-2 record with a touchdown, six interceptions and a 59.2 quarterback rating.

While it’s only Week 2, this is a potential season-defining game for the Bears. Teams that start out 0-2 have only a 12 percent chance of making the playoffs in the wild-card era. This game will come down to which team does a better job of protecting the football and stopping the run.

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Dan Durkin covers the Bears for CBSChicago.com and is a frequent contributor to 670 The Score. Follow him on Twitter at @djdurkin.