When training camp concluded in early September, the Packers raised a few eyebrows when they kept 11 defensive linemen on their 53-man roster. A bit of overkill, some thought, to have more than 20 percent of your roster consumed by one position group.

But the decision was in keeping with a core philosophy of Head Coach Mike McCarthy and General Manager Ted Thompson, that the foundation of any team is up front, which on defense means the defensive line.

And a corollary to that is this: With more-than-sufficient depth on the defensive line, the heart of your defense will never be entirely compromised by injuries. There will always be quality players, in the trenches, who can fill the gaps.

That philosophy has paid dividends throughout this season for the 10-1 Packers and has become most valuable in the last couple of weeks.

When defensive tackle Johnny Jolly was lost to a shoulder injury against Carolina on Nov. 18, veteran Colin Cole stepped into the rotation in Detroit on Thanksgiving and made a significant impact.

Then when Cole went down in Detroit with a fractured forearm, and with defensive end Kabeer Gbaja-Biamila already out with ankle and knee injuries, end Cullen Jenkins was needed on the interior and Michael Montgomery and Jason Hunter held their own on the outside.

And now, heading into the season's biggest game to date at 10-1 Dallas, that depth on the defensive line will be called upon once again.

Jolly isn't ready to return yet, and Cole has been put on injured reserve and is out for the season. So rookie first-round draft pick Justin Harrell, who hasn't played since injuring his ankle against Washington on Oct. 14, will be asked to take the No. 3 tackle spot behind starters Ryan Pickett and Corey Williams. Non-drafted rookie Daniel Muir, the only one of the 11 defensive linemen yet to play in a game, also could be activated for the first time.

On top of that, with Gbaja-Biamila's status a bit uncertain this week, Montgomery (who recovered from a knee injury of his own earlier this season) and Hunter may have to step forward again and take defensive snaps along with their special teams work.

"It's huge obviously," Pro Bowl defensive end Aaron Kampman said of having so much quality depth. "Some people questioned why we kept so many guys, but I think it says a lot about the people that make those decisions. They knew what they were doing, and it's kind of cliché, but you can never have enough defensive linemen, and I think that's really the truth. We're seeing that now with the rash of injuries we've had."

The impact of the reserves in Detroit last week was significant.

Before breaking his arm, Cole had posted five tackles and a pass deflection from his tackle spot.

Montgomery, who plays defensive end on run downs when needed, stopped running back T.J. Duckett for a 1-yard loss in the third quarter and Kevin Jones for a 4-yard loss near the goal line in the fourth quarter.

And Hunter, who took Montgomery's spot in passing situations, pressured Detroit quarterback Jon Kitna into an incompletion (recording a quarterback hit) in the second quarter, and he chased Kitna down on a scramble in the fourth quarter for just a 6-yard gain.

"That was outstanding -- I was extremely proud of how they fought and kept fighting through," defensive tackles coach Robert Nunn said of how the line held together. "They were honest with each other. If they needed a blow, they'd talk to each other and come in and out. They worked with (defensive ends coach) Carl (Hairston) down on the field as far as the substitutions. But they fought."

{sportsad300}This week, many eyes will be on Harrell with the important role he'll have to play spelling Pickett and/or Williams against the league's No. 2 offense. The Packers will be looking for their defensive tackles to anchor well against Dallas running backs Marion Barber III and Julius Jones as well as collapse the pocket on quarterback Tony Romo.

The No. 16 overall pick in the April draft, Harrell sat out much of the offseason with a bicep injury from his senior year at Tennessee, and he was inactive for the first four games of this season.

When he made his pro debut against Chicago on Oct. 7, Nunn said the game was moving pretty fast for him, but he was adjusting and continuing to make progress the following week against Washington, when he threw a key block on Charles Woodson's 57-yard fumble return for a touchdown.

The ankle injury set him back again, but Nunn said Harrell has kept up his mental progress even when he's been physically limited, so he has no concerns he'll be caught off-guard by anything he sees in Thursday's game.

"He's sharp," Nunn said. "Even when he wasn't getting reps back in the OTAs, he knew exactly what we were doing when somebody made a mistake. He knew what was going on. When we had a blitz walk-through, he was sharp on it. His approach has been very good throughout, through the injury in the offseason and through the injury here."

Harrell said this week the ankle is no longer a problem, and he won't be awed by the bright lights of such a big NFC showdown, even if it is his first game in seven weeks.

"Playing in a college like Tennessee, it prepares you," he said. "All the games you play are pretty much big games, and it doesn't get bigger than this -- 10-1 teams, spotlight game on Thursday night, so we've got to be ready.

"It's what I've been waiting for. I've been waiting for my chance, and I figure it's here now so I have to make the best of it."

That's what the Packers are counting on, and why the quality depth on the unit is there.

"He's going to be expected to go right in there and for us not to shift gears," Nunn said. "And I firmly believe that we won't."