By Dan Durkin-

(CBS) After putting up 21 points in back-to-back weeks against Tampa Bay and Minnesota, the Bears face a much stiffer challenge on the road this Thursday against Detroit.

The Lions are allowing a league-low 17.3 points per game (15 points per game at Ford Field). Everything starts up front with the Lions, who has the full attention of the Bears’ offense.

“Their speed,” Chicago coach Marc Trestman said of what stands out. “They’re physical. They’re penetrators, they’re relentless to the football. That’s where it all starts for them up front — not just the way they play the pass, but they play the run extremely well, as we all know.”

Through 12 games, the Lions are allowing a league-low 70 rushing yards per game. By making teams one-dimensional, they are able to pin their ears back and get to the quarterback. They go eight deep along the defensive line, and that rotation to keep players fresh.

Last week, the Patriots hung 34 points on the Lions, which was the most points Detroit has allowed all season. Bears quarterback Jay Cutler hoped to pick up a few pointers on the film.

“They spread them out a little bit,” Cutler said. “They ran the ball some. I think they threw it 40-50 times on them, a lot of empty (no running back in the backfield). They tried to neutralize it that way.

“Against a team like this you’ve got to get the ball out, you’ve got to get some catch-and-runs. You’ve got to break some tackles because you’re not going to be able to consistently push it down 15-20 yards. A lot of things are going to be under 12 yards, under five yards, so you’ve got to get some catch-and-runs. That’s where you’re going to get your pushes down the field.”

Line games

Defensive coordinator Mel Tucker is the object of heavy criticism in Chicago for the unit he coordinates. However, credit must also be given for his game plan last week against the Tampa Bay, as the Bucs’ protection schemes were scrambled.

Tucker frequently mixed in a fifth rusher from the second-level of the defense, then ran stunts and twists on the interior of the line to create single-block opportunities. The Bucs didn’t properly adjust by providing extra help, and the Bears’ defensive line capitalized.

“I thought there was good communication on some of those twists and stunts,” Tucker said. “Guys were on the same page. I thought we had pretty good coverage behind it. It was another example of rush and coverage working together to affect the quarterback.”

Defensive tackle Stephen Paea had a monster game, but the presence of Jeremiah Ratliff on the interior has helped solidify the Bears’ defensive front. Ratliff’s physical skills are obvious, but his football smarts are equally beneficial to help the Bears run some of their line games.

“He’s a very smart football player right in the middle of our defense,” Tucker said. “He’s got excellent awareness. He does set a lot of our games and things like that for us.”

Injury update

The Bears are only holding walk-throughs as they install their game plans in all three phases. Because they aren’t practicing, the injury report (full list below) is simply a projection.

Cornerback Kyle Fuller (knee) and linebacker Lance Briggs (groin) wouldn’t have participated. Trestman provided little clarity about their availability for Thursday.

“It’ll be probably — we’ll have a report out today and we’ll see where we are. It could go up to prior than 90 minutes before the game,” Trestman said.

Left guard Brian de la Puente also wouldn’t have participated due to an ankle injury, but right tackle Jordan Mills would’ve been a full participant. Offensive coordinator Aaron Kromer confirmed that if Mills is good to go, Michael Ola would slide to left guard and replace de la Puente.

Didn’t participate:
— LB Lance Briggs (groin)
— CB Kyle Fuller (knee)
— DT Jeremiah Ratliff (knee)
— OG/C Brian de la Puente (ankle)
— DE Trevor Scott (knee)
— LB Darryl Sharpton (hamstring)
— WR Chris Williams (hamstring)

Limited participation:
— WR Brandon Marshall (ankle)
— S Brock Vereen (shoulder)

Full participation:
— RT Jordan Mills (rib)
— G/T Eben Britton (appendectomy)

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