EUGENE — As far as national perceptions go, this win was as big as they come for Oregon, coach Mike Bellotti said after his No. 5 Ducks defeated No. 9 USC 24-17 Saturday in front of the largest crowd in Autzen Stadium history.

EUGENE — As far as national perceptions go, this win was as big as they come for Oregon, coach Mike Bellotti said after his No. 5 Ducks defeated No. 9 USC 24-17 Saturday in front of the largest crowd in Autzen Stadium history.

The reasons are plenty for that.

The Ducks (7-1, 4-1 Pac-10) kept their Pac-10 title hopes alive and remain in the hunt for a Bowl Championship Series' bid, while at the same time putting USC's (6-2, 3-2 Pac-10) BCS hopes in serious jeopardy.

Oregon entered the day No. 5 in the BCS and controls its own fate with just one Pac-10 loss to California and another marquee matchup awaiting next week with Arizona State at Autzen Stadium.

"Any time you beat USC it's a great feat," linebacker John Bacon said. "We knew going into this we had a great shot of doing something very special and displaying how good we are."

The Ducks certainly did that Saturday.

Consider the opponent, USC, which has been the Pac-10 Conference king since 2002 and, in that time, derailed many of Oregon's hopes in the process, including handing the Ducks their only conference loss in 2005.

"SC is a very good football team," Bellotti said. "They are as talented a football team as we're going to see this year. At least I hope so. I don't think our kids wavered in their belief of what we could do.

"This was a great win, simply because USC has been the flag-bearer for this conference for five years."

Consider also the way Oregon won the game, overcoming two special teams' turnovers in the first half — certainly a contrast from last season when turnovers sent Oregon into a downward spiral.

And in a game that was supposed to feature Oregon's high-powered offense, ranked second in the nation, and USC's lightening-quick defense, ranked third in the nation, it was the Oregon defense that stole the show.

"This was a defensive victory," Bellotti said. "We put our defense in a difficult hole and they really did a great job."

The Ducks allowed 378 total yards, butmade key plays when it counted. Free safety Matthew Harper came up with a timely interception to halt a USC drive in Oregon territory in the third quarter and again picked off USC quarterback Mark Sanchez to clinch the victory with 11 seconds left in the game after the Trojans had marched 50 yards in search of the tying score.

"Last year it was pretty embarrassing when we went to the (L.A.) Coliseum," Harper said, referring to Oregon's 35-10 loss. "We felt like we had a lot to prove."

The Oregon defense even set up the Ducks go-ahead touchdown by forcing a fumble on the USC 16. Two plays later, running back Jonathan Stewart, who had 25 carries for 103 yards and two scores, dashed 16 yards through the vaunted USC defense to give Oregon a 17-10 lead.

It wasn't always pretty for the Ducks' offensively. The final numbers read: a season-low 339 yards and punts on its final three possessions. Heisman hopeful Dennis Dixon was effective on the ground with 76 yards on 17 carries, but was held to just 157 yards passing on 16-of-25 completions.

So Saturday, it was the defense to the rescue and they set the tone early by stopping USC on a fourth-and-one attempt after the Ducks' Andre Crenshaw fumbled the opening kickoff.

"Those were unbelievable plays," Bellotti said. "A team the caliber of SC to get that big break early and get no points out of it was unbelievable.

"It really was a momentum changer."

After USC went three-and-out on its next possession, the Ducks drove 72 yards in 13 plays for the opening touchdown, with a 2-yard option keeper by Dixon capping the drive and handing Oregon a 7-0 lead with 4:24 to play in the first quarter.

Oregon committed its second turnover when a punt bounced off the foot of the Ducks' Garren Strong at the Oregon 37.

But the defense again answered the call, holding the Trojans to a field goal.

Oregon tacked on a late field goal in the second quarter to take a 10-3 lead into the break. USC orchestrated a nine-play, 62-yard drive to open the second half capped by Sanchez's 9-yard pass to Patrick Turner.

Oregon regained the lead at 17-10 with Stewart's 16-yard dash and the Ducks took a two-score lead with a key drive early in the fourth quarter.

The big play of the drive was Stewart's 15-yard run to the USC 47 on third-and-14. Stewart plunged in from a yard out seven plays later to give Oregon a 24-10 lead.

The Trojans made things interesting late when Sanchez completed four straight passes, the last to David Ausberry for a 14-yard touchdown with 4:44 remaining in the fourth quarter.

Sanchez finished the day 26-of-41 for 277 yards, two touchdowns but two costly interceptions.

The USC defense forced a three-and-out on Oregon's next possession, and the Trojans took over with 3:10 to play at its own 17, before Harper sent the 59,277 into a frenzy with a game-saving interception.

"Our defense plays for those moments," Harper said. "We want to play at the last minute. We want to show everyone what we are about."

Saturday, they showed the nation.

Reach reporter Luke Andrews at 776-4469, or e-mail landrews@mailtribune.com