The Packers have a few different options for how to go about replacing middle linebacker Nick Barnett for this Sunday's game, but one option apparently received the most attention on Wednesday.

During the jog-through portion of practice that was open to the media, A.J. Hawk lined up in Barnett's middle linebacker spot with Brandon Chillar working with the first unit at Hawk's usual weak-side position. Brady Poppinga remained in his normal strong-side spot.

But the defense is preparing for other scenarios as well. Head Coach Mike McCarthy said all the linebackers, including Desmond Bishop - who replaced Barnett during the second half last Sunday after Barnett tore the ACL in his knee, ending his season - are being double-trained at the inside and outside spots this week to give the unit the most flexibility for any adjustments that are needed.

"A.J. is getting a lot of work there, and we just have to be ready just to be able to move in and out of our different personnel groups," McCarthy said.

If Hawk ultimately is the choice in the middle, he says it won't be that big a change for him. In college at Ohio State, he played both inside and outside at linebacker, and he said being in the middle simply presents a new way to see the play unfold.

"It's just kind of seeing the game from a little different perspective, being in the middle of the field and running inside-out to all the plays instead of chasing things from the backside at the 'will' position a lot," Hawk said. "I think it just takes a little bit of work to keep that view, the different perspective of the game and to feel how they're trying to attack you and do things.

"It's tough losing a guy like Nick that's been doing it for so long here. That's why all of us as linebackers here need to make sure we step up and pick up the slack for him."

In addition to being the fiery, emotional leader of the defense, Barnett also wore the new helmet speaker to communicate the calls from defensive coordinator Bob Sanders to the huddle. Hawk took over wearing the helmet speaker after Barnett went down last week, and he expects to have that responsibility again.

"The last couple games, you always have to have backup guy for the speaker, and that was me," Hawk said. "Last week was the first time I had to do it, but it was fine. I enjoyed it. I like being in there in control of the huddle, calling the defense. It keeps you in the game."

All the cross-training going on with the core linebacking group will give the defense options to cover any other substitution or injury-related scenarios.

Chillar was a late scratch from the active gameday roster last week when a shoulder problem flared up on him the night before the game. He was a full participant in practice on Wednesday, but the workout was not in pads, whereas Thursday's practice is scheduled to be.

If Chillar is unable to play once again, the defense would have the choice of keeping Hawk in the middle and starting Bishop on the weak side, or moving Hawk back to the weak side and starting Bishop in Barnett's place. Or possibly moving Poppinga to a new spot if needed.

"All of us linebackers have rotated through all three positions," Hawk said. "In mini-camp, OTAs, even during the season we'll do that. It's not anything I haven't seen or any of the linebackers haven't seen. It's just all about getting reps and getting comfortable."

Bishop said it appears once again he'll need to be the linebacker ready-in-waiting. He made one big play in Barnett's place last Sunday, stripping the ball from running back Adrian Peterson on a fourth-and-1 midway through the fourth quarter.

But his two mistakes overshadowed that. On his first snap, he overran running back Chester Taylor in the flat on his 47-yard catch-and-run for a touchdown. And late in the game, he didn't fill the run gap on Peterson's game-winning 29-yard TD run.

Bishop can't help but wonder if he'd be the clear-cut choice to fill Barnett's shoes had he not made those errors, but he's going to get ready to play at any spot, regardless.

{sportsad300}"You can't think like that, but then again, it's in the back of my mind," Bishop said. "If those two plays would have went the way I wanted them to, then maybe they might have had a little more confidence in me. But you can't go back. Only look forward."

That's what the defense as a whole is doing, both with respect to replacing Barnett and trying to stop the run.

With the team as healthy as it could be following the bye week, the hope was the run defense would improve, but instead Tennessee and Minnesota combined for 398 rushing yards in the last two games.

While this week's opponent, the Chicago Bears, ranks 15th in rushing offense and isn't as highly touted in that department as the Titans (6th) and Vikings (5th) are, rookie running back Matt Forté is still eighth in the league in rushing yards with 713. So the Packers, and their new linebacker alignment, expect to see plenty of the former Tulane star on Sunday.

"Once you've shown something on film that you haven't done real well, I think a team should come in and try to test that and see if you've cleaned it up and if you can stop it," Hawk said. "We haven't been stopping the run like we should, so we expect everyone to test us."

The new linebacker configuration coming Sunday is perhaps a test run for the remainder of the season. With seven games left, replacing Barnett is a long-term proposition, but the group currently assembled is trying to prevent it from being even a short-term liability.

"It gives other guys an opportunity to step up," defensive end Aaron Kampman said. "I've said all along I think linebacker is one of our greatest positions of depth, and now we get a chance to really reflect that and show that this Sunday."