PUSHING BACK

SOUTH BEND, Ind. -- They won their last game, not their last 27.

The quarterback is a sophomore making only his second start, not a senior Heisman Trophy winner prepped to make some of the most dramatic and historic plays in college football history.

But when Mark Sanchez leads USC against Notre Dame today at Notre Dame Stadium, there still will be plenty on the line for 13th-ranked USC in the 79th meeting between the intersectional rivals.

USC might be 14th in the Bowl Championship Series standings, but in this upset-mad season, the Trojans remain in the hunt for a berth in the BCS title game.

Coach Pete Carroll’s more immediate concern, however, is getting his team to perform consistently well.

The Trojans play their annual nonconference game against Notre Dame after three uneven Pacific 10 Conference performances. The Trojans narrowly defeated Washington at Seattle, lost in a stunning upset against Stanford at the Coliseum, and last week defeated Arizona at home in Sanchez’s first start.

“This is an enormous opportunity to come off last week and get going again,” said Carroll, who has won five consecutive games against the Fighting Irish.

Much has changed since the Trojans’ last visit to South Bend.

Two years ago, quarterback Matt Leinart’s clutch fourth-and-nine pass to wide receiver Dwayne Jarrett and the infamous “Bush Push” that propelled Leinart into the end zone in the final moments gave the top-ranked Trojans an epic 34-31 victory over the ninth-ranked Irish.

USC went on to play in the BCS title game against Texas, Notre Dame in the Fiesta Bowl against Ohio State.

As it did in 2005, USC began this season ranked No. 1. But the Trojans created a long journey back to national title contention by losing to Stanford, a 41-point underdog.

Quarterback John David Booty suffered a broken middle finger on his right hand during the loss and Sanchez replaced him as the starter against Arizona the next week.

Booty, a fifth-year senior, threw passes during the week with a receiver’s glove on his throwing hand, but Carroll on Friday announced that Sanchez would start again.

“The opportunity to give [Booty] another week to heal without the rigors of playing through a game is really the idea,” Carroll said after the team’s walk-through at Notre Dame Stadium on Friday. “Anything can happen just playing.

“If we’re fortunate enough to put together a good football game and win, he’s a week better off for it. We may or may not have that luxury, I don’t know.”

Sanchez completed 19 of 31 passes for 130 yards against Arizona, overcoming two first-half interceptions and throwing a 25-yard touchdown pass to tight end Fred Davis for what proved to be the winning points.

“First-game jitters are out,” Sanchez said this week. “I’m ready to really play and be efficient.”

Sanchez will operate behind an offensive line besieged by injuries. Redshirt freshman Butch Lewis is expected to start in place of All-American left tackle San Baker, who suffered a strained hamstring against Arizona. Alatini Malu is expected to start in place of guard Chilo Rachal, who is still recovering from a knee injury.

Struggling Notre Dame feels no sympathy for the Trojans.

Like USC, Notre Dame is in a different place than in 2005, when quarterback Brady Quinn and other juniors and seniors nearly ended what would grow to a 34-game winning streak.

The Fighting Irish are 1-6, their only victory coming against UCLA at the Rose Bowl two weeks ago.

“More than anything there’s been -- like every program, OK -- a significant transition,” Coach Charlie Weis said. “But the problem is the transition has been mainly to younger guys, not to another group of juniors and seniors.”

Notre Dame’s offense ranks among the nation’s worst in several categories. The Irish rank last in total offense (190.9 yards a game) and rushing (32.1 yards a game), and next to last in scoring (11.4 points).

Junior Evan Sharpley replaces freshman Jimmy Clausen at quarterback and will make his first start behind an offensive line that has given up 34 sacks.

USC’s defensive line, which ranks last in the Pac-10 with only 12 sacks, senses opportunity.

“If they’re giving up sacks like that we have to take advantage,” defensive end Kyle Moore said.

Carroll is hoping for a fast start and more opportunities for freshman Joe McKnight to run the ball and return punts. But given the way USC has performed this season, he expects another difficult game for the Trojans.

“They’re finding themselves and trying to get on track with a bunch of new starters and new guys as well,” Carroll said of the Fighting Irish. “This [game] could be just like the rest of them.”

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gary.klein@latimes.com