The nose tackle's job -- on a lot of teams -- is pure grunt work. Absorb blockers, clog the middle, let the linebackers run free.
The USC defensive scheme calls for something different. The Trojans want their man in the muck to be disruptive, moving quick and low, using leverage to shed blocks and pursue the ball.
"It's a focal point," defensive coordinator Nick Holt said. "When we have good nose tackles, we're really, really good."
The last two starters at the position -- Mike Patterson and Sedrick Ellis -- left campus as All-Americans. Now, while much attention has focused on newcomers at quarterback and along the offensive line, the Trojans have a crucial opening on defense.
A few days into camp, junior Averell Spicer and sophomore Christian Tupou lead a mix of possibilities, with the additional option available of shifting senior Fili Moala, the starter at the other tackle spot, to help out.
The candidates are feeling the responsibility.
"It's like someone coming up and slapping you in the face," said Tupou, casting the situation in lineman's terms. "You've got to do something back."
The 6-foot-2, 295-pound Spicer ranks as heir apparent. Similar to Ellis in body type -- that quick and low thing -- he played enough last season to gain experience at the position.
But a bruised knee required off-season surgery, causing him to sit out spring practice and summer sessions.
"When guys were working out, I had to sit back and watch," he said. "They're looking at you like you're getting a break, but you're not. You want to be out there."
The younger Tupou spotted an opportunity.
At 6-2, 280 pounds, the sophomore impressed coaches in spring ball, then said he spent a good portion of his summer holed up in the football offices and in his dorm, watching films of Ellis and veteran teammate Moala.
"Their techniques, the way they play the run and their pass rushes," he said. "I'm trying to steal whatever they have so I can play at their level.
"It could be just one thing. How vicious they do the rip or how quick their first step was. Then I'll come out the next day and say this is my 'first step' day or my 'vicious rip' day."
The Trojans' recent tradition at nose guard began with Patterson, who showed up as an overweight freshman in 2001 and worked himself into a senior All-American, drafted in the first round by the Philadelphia Eagles.
His play was predicated on unusually quick hands and a low center of gravity.
"He set the example of what a USC nose tackle was really supposed to be all about," Ellis said in 2005.
More of a strength player, Ellis did him one better by making All-American twice, and recently signed as a first-round pick with the New Orleans Saints.
Spicer said he learned from both men. Patterson told him during a recruiting trip to focus on a quick start, while Ellis taught him to get after the ball.
"Say the center doesn't try to block me, I have to get a hand on him to slow him up from getting to the [linebacker]," Spicer explained. "But I don't have to take that block for the next guy. I just have to give them a chance to beat the center and I get freed up as well."
Given the inherent brutality of the position -- grappling amid 300-pound bodies, taking on multiple blockers -- the Trojans probably will need a couple of reliable nose tackles to rotate through the lineup as the season progresses.
Holt mentions freshman DaJohn Harris among other candidates. He would rather not shift Moala.
"We might do some of that," the coordinator said. "I don't think we're going to need to because I think Averell Spicer and Christian Tupou or one of those other guys are going to be just fine."
The coaches intend to bring Spicer along gradually over the next few weeks, allowing him to gain strength without reinjuring his knee. "He's working back in there," Holt said.
Spicer is less patient.
"Ever since I've been here, my philosophy is I can't let anybody younger beat me out," he said. "Now I'm the oldest nose tackle, so I plan not to let that happen."
As the elder statesman, Spicer appreciates not only the responsibility of playing his position, but also the potential rewards.
"I watched the guys before me," he said. "Our system, the way our defense plays, it gives the nose tackle a lot of opportunities to make tackles."