Starting two rookie linebackers isn't ideal for a defense facing quarterback Aaron Rodgers and the Packers' offense, but that's the situation the Bears could find themselves in Monday night.
Rookie Khaseem Greene worked with the first team Monday in place of injured weakside starter Lance Briggs, although coach Marc Trestman said he hasn't decided if the fourth-round pick will start in Green Bay. Second-rounder Jon Bostic already is the Bears' starter at middle linebacker.
"Khaseem will certainly get a very good look, (but) we've got Jerry (Franklin), and we've got Blake (Costanzo), and we just brought in (Larry) Grant," Trestman said. "But we'll start with Khaseem, and we'll see how the week goes."
Greene has played on special teams in each of the first seven games but has played just one snap on defense. It was seven-year veteran Costanzo, not Greene, who took over after Briggs suffered the fractured shoulder in Week 7 that is expected to sideline him for six weeks.
That 45-41 loss at Washington was the first NFL start for Bostic. He is filling in for 10-year veteran D.J. Williams, who is out for the season with a chest injury.
Monday night's challenge will be more difficult. The Packers' offense is No. 2 in the NFL, averaging 438.9 yards per game, and No. 3 in points, averaging 30.3. On paper that's a monumental mismatch against a Bears defense that is 27th in yards (391.0) and 29th in points (29.4) allowed per game.
The rookies, along with the other defensive starters, must be focused exclusively on their own assignments if they hope to contain Rodgers, fourth in the league with a 108.0 passer rating. Green Bay has the No. 5 aerial attack in the NFL, while the Bears are tied for 27th in passing yards allowed.
"The No. 1 way we can improve is by guys just paying attention to their job and not trying to make up for a younger guy or trying to do too much," Trestman said. "We really have to play together more than ever now."
And rookies can't try to do more than they're capable of, or try to be the player they're replacing.
"If I am the starter, I can't go out there and try to be Lance because I'm not him," Greene said. "I can learn from him, and I have learned a lot from him. But I can't go out there and try to force myself to make plays and stuff like that, or I'll end up hurting the defense and the team.
"So my main thing is just doing what I'm supposed to do."
Greene and Bostic both have benefited from being in the same linebacker room as old pros Briggs and Williams, plus eight-year veteran James Anderson, the only original starter still on the field.
But the rookies will have to rely on each other when they're on the field in Green Bay, much as they did in the preseason, when they played together frequently.
"We're going to depend on each other," Greene said. "We're going to have to help each other. We have to do a lot of talking out there, get our chemistry back that we had throughout preseason."
After reviewing film of his first start, Bostic said he "has a long way to go. There's something on every play I can say that could have made a difference in the ballgame."
Bostic said practicing against the Bears' offense would help Greene, just as it has helped him because it provides excellent preparation for the real thing.
"Really it's not an adjustment because he'll be going against good players every day in practice," Bostic said. "We do a lot of ones on ones, so he's getting a chance in practice to go against Brandon Marshall and Martellus (Bennett). He's going against guys every day that he's pretty much going to see on Sunday."
Greene already has figured out that the jump from college to the NFL is huge, and it has required him to be diligent in his off-the-field preparation to keep pace.
"You go from high school to college and the guys are a little bigger and faster," said the 6-foot-1, 241-pounder. "You go to 'The League,' and guys are a lot bigger and faster. There are linemen in the league who run just as fast as you, so now it's more focusing on the mental things that give you an edge.
"That's been a big adjustment for me; studying film, watching Lance, watching James and those guys and how they prepare throughout the week, and then building my own routine and getting into the flow of things."
The current gets a lot swifter Monday night.
•Cornerback C.J. Wilson was waived Monday and then signed to the practice squad.
•Follow Bob's NFL and Bears reports on Twitter @BobLeGere.