Aaron Kampman brought leadership, tenacity, production and a strong work ethic to Jacksonville's defense this season.
The Jaguars are about to find out if those qualities rubbed off on his young teammates.
Kampman tore the anterior cruciate ligament in his right knee during practice Thursday, leaving the Jaguars without their best pass rusher and their defensive leader.
Kampman injured his knee during a non-contact drill. Tests Friday revealed the severity of the injury. He will be placed on injured reserve and have surgery at a later date.
"It's a shame because he's a special young man in a lot of different ways, not only on the field but in the locker room, in the community," coach Jack Del Rio said.
The Jaguars (4-4) signed Kampman to a four-year, $26 million contract in March to upgrade a defense that had a league-worst 14 sacks in 2009.
Jacksonville felt like it was getting a bargain even though Kampman tore the ACL in his left knee last November. He recovered in time to make an immediate impact this season and leads the team with four sacks and 30 quarterback pressures.
"Any time you have one of your main guys out for the year, especially with a guy that's not just a starter but an impact player, it hurts," cornerback Rashean Mathis said. "It hurts a lot. But those things happen all the time in the league, week-in and week-out it's bound to happen."
Without Kampman, the Jaguars are expected to move Jeremy Mincey to the right side and insert former first-round draft pick Derrick Harvey back into the starting lineup. Mincey has a broken right hand, but is expected to play with a small cast.
"I'm just going to have to step it up another notch," Mincey said. "I'll get the job done, even with a broken hand. That's not going to keep me from emerging. Everybody has to play better. That's the nature of this game. It's what you have to do if you're going to be successful."
Harvey, the eighth overall pick in 2008, has been mostly a disappointment in three seasons. He was benched two weeks ago, but now gets a chance to redeem himself.
"There is a void there and we have to realize that," Mathis said. "The guys who are stepping up have to realize that the guy they're replacing played some good football. They have to be willing to step up and be able to give us something, give us an impact."
Rookies Larry Hart, Austen Lane and Aaron Morgan also will get more playing time.
But it remains to be seen whether a first-round bust, an oft-injured player with potential and three rookies will be able to fill Kampman's shoes.
Practicing in shorts, his No. 74 jersey and a helmet, Kampman tweaked his knee when he planted his right leg during a pass-rush drill. He immediately suspected it was a torn ACL since he did the same thing to his other knee less than a year ago.
"It's not a feeling you forget or want to feel again," Kampman said.
But he held out hope until tests proved otherwise.
"It's disappointing, definitely," Kampman said. "I can honestly say that this last experience has made me a better man, has made me stronger. I have learned tremendous lessons through it and I guess I've got more lessons to learn. I'll attack it with the same vigor that I did previously and continue to move forward.
"Being a man of faith, I believe you're never given more than you can handle. This is definitely another big one, but ... there's more lessons to learn."