LOS ANGELES — Each of the past two years, mighty Southern California was knocked off by a Pac-10 underdog. Each time, the Trojans bounced back with some impressive victories — and then lost again.

They've already had their first shock of the season, in their conference opener at Oregon State last week. Another loss almost certainly would knock USC out of national title contention and dent their chances of a seventh consecutive Pac-10 title.

Dropped from No. 1 to No. 9 following their 27-21 loss at Corvallis, the Trojans (2-1, 0-1) try to return to form when they face No. 23 Oregon (4-1, 2-0) Saturday at the Coliseum.

"An opportunity is what this is," USC coach Pete Carroll said. "We want to see our guys find our way to get the focus that takes us right back to the way we're capable of playing.

"That's what we do. We've done this before and been in this situation."

The Ducks beat USC 24-17 at Eugene last year, but still couldn't break USC's grip on the Pac-10 title and Rose Bowl berth.

"There are all those different elements there, playing in a huge game in the Coliseum on national television," Ducks quarterback Jeremiah Masoli said. "We've just got to stay level-headed like we were playing (Washington State) last week."

Watching USC's loss to Oregon State last Thursday probably gave the Ducks clues to what might work against the Trojans' defense. USC had all kinds of problems tackling 5-foot-7 freshman Jacquizz Rodgers, who rushed for 186 yards and two touchdowns to key the Beavers' victory.

The ground game is Oregon's strong suit, with their running back tandem of LeGarrette Blount and Jeremiah Johnson. Blount has averaged 7.3 yards a carry and 96.2 yards a game and scored eight touchdowns, while Johnson has averaged 6.8 and 88 and has scored six TDs.

USC defensive end Kyle Moore said the Trojans didn't do a good job of getting rid of their blockers and spotting the diminutive Rodgers.

"This week, the coaches have been telling us that we have to beat the man in front of us first, then worry about the runner," Moore said.

The Ducks' ground attack has helped them survive a string of quarterback injuries. Starter Nate Costa was lost of the year in the preseason to a knee injury. Second-stringer Justin Roper been in and out of the lineup with a knee injury. Either he or Masoli, who had been No. 3 on the depth chart, will start against USC.

Trojans quaterback Mark Sanchez had the look of a Heisman candidate against Virginia and Ohio State before the Trojans stumbled in Corvallis. Their committee of tailbacks, led by Joe McKnight, also sputtered against the Beavers.

Sanchez's former high school teammate, Ducks defensive end Nick Reed, is Oregon's best pass rusher. He already has 8.5 tackles for loss, five sacks and a fumble recovery.

The Trojans are expected to be without middle linebacker Rey Maualuga, one of their defensive mainstays who has a knee injury.

Although USC is coming off a surprising loss, the Ducks figure the Trojans will be the same as usual.

"Every time I watch USC, they seem pretty even-keeled," Oregon center Max Unger. "Maybe it's their coaching or how they play or that they have All-Americans backing up All-Americans, but it kind of seems like they don't get super ridiculously fired up or play down to anybody."

Ducks coach Mike Bellotti wants to make sure his 60 players from California don't get distracted.

"We talk about first and foremost, it's a business trip," he said. "It's not a visitation, it's not a vacation. It's go there to do our business, and that's play our best football and win the game.

"The second thing is, we always talk about the fact you have to control your emotions so they work for you, not against you. It's an opportunity to play for friends and family for maybe the first and only time this year."

Although USC holds a 36-16-2 record in the series that began in 1915 and is 19-7-1 in the last 27 games, the Ducks have won five of the last eight and six of the last 10.