By Dan Durkin-

(CBS) The Bears have now begun two weeks of bizarre practice schedules, given their back-to-back Thursday games. This week’s schedule is even more compressed as the team plays an early game this Thursday on the road in Detroit.

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Bears coach Marc Trestman said the focus has quickly shifted to the Lions, and the game plans were being installed Monday at Halas Hall for all three phases.

“Players will come in tomorrow,” Tresman said. “We’ll have multiple meetings and multiple walk-throughs to try to get through all phases, and then we’ll leave on Wednesday, get over to Detroit and the game will be here very quickly.”

While the Bears have won two straight games against teams with a combined six wins, the Lions have lost two straight games to the two teams who share the league’s best record, the 9-2 Arizona Cardinals and New England Patriots. Not only have the Lions lost, their offense hasn’t scored a touchdown in either game.

Trestman was complimentary of the Lions defense, but he also knows the Bears are going to face a desperate offense that has a lot of talent.

“Obviously their pass rush,” Trestman said. “Going into this week they were No. 1 in the league in defense, and run and pass are close to it at the top. Very, very good pass rush. Their back end is playing very well in continuity. We know what they have talent-wise offensively, and we know that they haven’t opened it up the last three weeks and it hasn’t happened for them. That will be a challenge for us coming into Thanksgiving, for our defense knowing where their offense is right now, knowing that they’re close to wanting to break things wide open as well.”

Performance of offense has been ‘disturbing’

Obviously, the Bears offense has regressed significantly in Trestman’s second season on the job. Against Tampa Bay, they mustered only 69 yards in the first half and ended with 204 total yards. The Bears had seven three-and-outs and only one drive longer than 26 yards.

“It’s been disturbing that we haven’t been able to move the ball the way we would like to in games; that’s a fact,” Trestman said. “But just based on where we’ve been over the last five or six weeks, no doubt about it. We’ve got another opportunity Thursday to move forward, and we’re going to do everything we can to get that done. It’s not what we want.”

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The Bears never found a rhythm Sunday, which took them out of their game plan. Most of the issues the Bears had to work through were self-induced.

“Overall, I thought our whole offense was just very, very poor early because of the mistakes that we made,” Trestman said.

The Bears wanted to get quarterback Jay Cutler on the move, as they did a week prior against the Vikings. It was needed given the consistent pressure he was under in the first half, but their game plan was derailed early on, Trestman said.

“We were so out of sequence in the first half, we didn’t get as much opportunity to do that (move Cutler in the pocket),” Trestman said. “We did it a couple times. We hit Marty (Martellus Bennett) in the flat on one, and Marty made a nice catch on the over route on the other one. I don’t know that we were going to run it anymore, but we were out of game plan or out of sync with our game plan in the first half.”

Injury update

The Bears played the majority of Sunday’s game without linebacker Lance Briggs (groin) and cornerback Kyle Fuller (knee). On Monday, Trestman wouldn’t say whether their injuries were season-ending.

“Right now it’s on ongoing situation today and as we gather information all I can do is leave it at that, and we’ll see where things are tomorrow,” Trestman said.

In their place, Jon Bostic would slide over to the weak-side linebacker spot and potentially be joined by Christian Jones in nickel packages, while Al Louis-Jean would replace Fuller.

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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.