A week after facing the league's second rated defense in the Houston Texans, the Bears travel to San Francisco Monday night to face the league's third rated defense. Through nine games this season, the 49ers have given up just 292.1 yards per game.
Much like the Bears, the 49ers are a team built around their defense and their star inside linebacker.
Patrick Willis has been a monster at inside linebacker since he was drafted 11th overall in the 2007 draft. He has made the Pro Bowl each of his first five seasons and is on pace to go to his sixth straight following this season. He is a tremendous tackler, already racking up 72 this season to go along with a forced fumble and an interception.
Much like Willis, Navorro Bowman, the other inside linebacker in the 49ers 3-4 scheme, is a tackling machine, leading the team with 81 tackles. Bowman has more a knack for getting to the quarterback, racking up two sacks this season and one interception.
Both inside linebackers struggled at times last week against the St. Louis Rams and running back Steven Jackson, but they still can pose trouble for the Bears' running game. With a concussion likely going to keep quarterback Jay Cutler out, the Bears will try and utilize more of Matt Forte and Michael Bush in the running game.
It is not easy to attack the middle of the field, but the offense linemen, particularly the interior of Chilo Rachal, Roberto Garza, and Lance Louis, will need to do a good job at getting themselves up field to block the quick and elusive inside linebacker duo. Expect the Bears to take advantage of their willingness to cheat up against the run by using draws and/or screens.
The defensive line for the 49ers is anchored by Justin Smith, who has yet to get a sack this season. Smith is a great bull-rusher, strong against the run and his relentless motor will give left tackle J'Marcus Webb all that he can handle.
Nose tackle Isaac Sopoaga is the prototypical nose in a 3-4 scheme and does a good job at plugging gaps and funneling runners towards the linebackers. Left end Ray McDonald is the lone defensive lineman credited for getting to the quarterback with a half sack he registered against Matthew Stafford in Week 2.
All three defensive lineman do a good job of slowing down the running game and the Bears offensive lineman will have to be physical and use leverage and strength to move their defender.
Despite the lack of pressure from the defensive line, outside linebackers Aldon Smith and Ahmad Brooks have had their fair share of success with getting to the quarterback.
Smith dominated in his rookie season, getting to the quarterback 14.5 times and causing matchup problems week in and week out. This season, through nine games, he has racked up 9.5 sacks despite seeing an increase in his role. His long arms and athleticism makes him so difficult to stop and with his new found abilities in pass coverage, he is shaping into one of the best young outside linebackers in the game.
Opposite of Smith is veteran Ahmad Brooks. Drafted in the third round of the supplemental draft in 2006 by the Cincinnati Bengals, Brooks has excelled in his role since his arrival in San Francisco in 2009. Brooks has four sacks on the season and because of his ability to rush the passer, teams cannot afford to double team Smith therefor opening more opportunities for his fellow outside linebacker.
Both Smith and Brooks understand that tackles Gabe Carimi and J'Marcus Webb have struggled this season and will likely be sent on blitzes more often than they have this season.
Webb will be saddled with the responsibility of going up against Smith and will be challenged by his ability to use his hands, something Webb has struggled with all season. Brooks is more of a straight line rusher, trying to shoot off the hip of the tackle. Carimi's struggles have been well documented this season in pass blocking, and the Bears will likely use a tight end of a chipping back to try and slow him down.
Dashon Goldson highlights the secondary with his abilities in both the run and passing game from his free safety position. He has the ability to come up and stop the run and plays very well in the cover-2 scheme they often run. He has a knack for punishing hits on the ball carrier and also is tied for the team lead with two interceptions.
He will be expected to come down and try to slow the running back tandem of Forte and Bush but will also likely have the responsibility to cover over the top of Brandon Marshall.
Next to Goldson at the strong safety position is Donte Whitner. He was a former first round pick of the Bills in 2006 and signed with the 49ers before the start of last season. He is stout against the run and much like Goldson, he is an extremely hard hitter and will make Earl Bennett and Devin Hester think twice about coming across the middle.
Carlos Rogers is the team's best cornerback and although he struggled at times last week against Danny Amendola, he is still a tough defender. He struggled at times against Amendola when he was lined up in the slot and the Bears would be wise to try Brandon Marshall there occasionally to get Rogers out of a rhythm.
Tarrell Brown and Chris Culliver are the number two and three cornerbacks and both have improved their play from last year. Culliver has excelled in the nickelback role, hauling in two interceptions this year. With the possibility of Campbell starting on Monday night, he'll have to be aware of Culliver's ability to jump on a route and take away the football.
Matt Eurich is a contributor to Bearsbacker.com. Follow Bears Backer on Facebook and Twitter for up to the minute news about the Bears. Also, check out Matt’s work on BleacherReport.com and follow him on Twitter @MattEurich.