It started outside the locker rooms before warmups, USC and Notre Dame players exchanging words.
"They were barking at us, so we barked back," USC defensive lineman Fili Moala said.
It continued as the teams made their way down the Coliseum tunnel.
"This is our house, so for them to come in and start something got to us," said USC defensive end Clay Matthews.
It erupted into a near-brawl as the teams got ready to take the field.
"That just adds fuel to our fire," USC defensive end Kyle Moore said, chuckling.
On a night already dripping with it for USC seniors playing their last game at the Coliseum, the Irish unwittingly added an extra dose of emotion.
What transpired afterward might be remembered as one of the greatest defensive performances in the history of this storied rivalry.
Fifth-ranked USC routed the Fighting Irish, 38-3, in front of an announced 90,689 at the Coliseum.
The Trojans did not give up a first down until the last play of the third quarter and lost their second consecutive shutout against Notre Dame only when embattled Irish Coach Charlie Weis opted for a 41-yard field goal while trailing, 31-0, in the fourth quarter.
USC's seventh straight win over the Irish improved its record to 10-1, and Oregon's victory over Oregon State on Saturday put the Trojans in the driver's seat for their fourth consecutive Rose Bowl game appearance heading into their regular-season finale against UCLA at the Rose Bowl.
Saturday's result also might have ended the tenure of Weis, who came into the game on the hot seat and left the Coliseum with the stadium burning with speculation about his future.
"Their defense whipped us pretty good tonight until the end of the third quarter," Weis said.
By then, the outcome had long been decided.
"For all of the seniors, everyone had something extra going," senior linebacker Rey Maualuga said. "Everyone was just having fun."
USC players seemed to enjoy the pregame scuffle, which was reminiscent of a mid-'80s melee in the tunnel at the Coliseum and a 1989 tunnel brawl at Notre Dame Stadium.
But USC, a 32-point favorite, did not allow the Irish a fighting chance.
In the first half the Trojans intercepted two passes, did not give up a first down and limited the Fighting Irish to nine yards en route to a 24-0 lead.
Notre Dame finished with 91 yards and converted only two of 14 third downs.
"It just seemed like series after series after series, nothing happened," USC Coach Pete Carroll said. "We really didn't have to do very much tonight, just play a solid base defense."
That defense is led by seniors who finished their careers undefeated against Notre Dame.
Moala, Matthews and Moore, linebackers Maualuga, Brian Cushing and Kaluka Maiava and cornerbacks Cary Harris and Josh Pinkard all played well and helped Carroll improve to 27-0 in November.
"We did it right," said Cushing, who had one of the Trojans' four sacks.
Irish quarterback Jimmy Clausen, a sophomore from Westlake Village Oaks Christian High, completed 11 of 22 passes for only 41 yards and had passes intercepted by Harris and Maiava.
"They are one of the top defenses in the country, if not the best," Clausen said. "They have one of the fastest pass rushes we've faced."
USC's offense struggled initially -- quarterback Mark Sanchez's first pass was intercepted -- but the Trojans overcame some fits and starts to finish with 449 yards.
Sanchez said he was angry after Notre Dame cornerback Robert Blanton intercepted his pass two plays after Harris had give the Trojans a break by picking off Clausen.
According to Sanchez, offensive coordinator Steve Sarkisian just smiled and said, "Let it go. Forget it. Let it rip."
"That's exactly what I did," Sanchez said.
Sanchez finished 22 for 31 for 267 yards and two touchdowns with two interceptions.
The Trojans built their halftime lead on a short touchdown run by Stafon Johnson, a 55-yard touchdown run by Joe McKnight, Sanchez's 12-yard touchdown pass to Damian Williams and David Buehler's 35-yard field goal.
Tailback C.J. Gable ran for a short third-quarter touchdown and Sanchez completed the scoring with a 17-yard strike to senior receiver Patrick Turner with 7:57 remaining.
After that, Carroll pulled the starters and the Trojans started looking ahead to UCLA.
USC seniors might have concluded their careers unbeaten against Notre Dame, but they still remember their 2006 loss against the Bruins. A pregame rumble with UCLA probably won't be necessary to motivate the Trojans.
"The last time we played them at the Rose Bowl, we lost," Cushing said. "So, we've got to come out and play a good game."
If the defense plays like it did Saturday, that should be plenty good enough.
Dec. 6, 1:30 p.m.
at the Rose Bowl
UCLA is out of bowl contention and coming off a 34-9 loss to Arizona State. The Bruins will be a heavy underdog against a Trojans team trying to secure a Bowl Championship Series bowl berth, but UCLA has shown in the recent past that it is capable of derailing USC. Few on either side of the rivalry will ever forget the Bruins' 13-9 victory at the Rose Bowl in 2006 that kept USC out of the BCS title game. This will be the first game matching USC Coach Pete Carroll against UCLA Coach Rick Neuheisel and former Trojans offensive coordinator Norm Chow.
-- Gary Klein