EUGENE, Ore. -- The defeat was not as shocking, but the recipe for USC's demise was virtually the same.
Intercepted passes. Fumbles. Penalties and missed opportunities.
Those were the miscues that hurt the Trojans in their embarrassing upset loss to Stanford four weeks ago.
On Saturday, the mixture cost them much more.
USC fell to 6-2 overall and 3-2 in the Pacific 10 Conference, its bid for a sixth consecutive league title possibly over.
"We missed a big opportunity today," Coach Pete Carroll said outside a somber locker room.
USC, which began the season a near-unanimous choice by pollsters and pundits to play in the Bowl Championship Series title game, now faces the prospect of finishing the season in a second-tier game such as the Holiday or Sun bowls.
"The standards are a lot higher here, but the reality is if you don't execute and play well enough to win, a good team like this is going to beat you," defensive end Lawrence Jackson said.
Oregon, led by multitalented quarterback Dennis Dixon, stayed on track for a possible berth in the BCS title game. The Ducks are fifth in the BCS standings and look like a team primed to take advantage of any slips by those ahead of them.
"We still have a lot to prove and I think we're ready to prove it," said Oregon Coach Mike Bellotti, whose team improved to 7-1 and 4-1 in the Pac-10 before a stadium-record crowd of 59,277.
On a clear and cool day, USC showed it had not learned some tough lessons from the Stanford debacle.
Sophomore quarterback Mark Sanchez, making his third consecutive start in place of injured John David Booty, had two passes intercepted by Oregon safety Matthew Harper in the second half. The first led to a fourth-quarter touchdown that gave Oregon a 14-point lead; the second ended USC's final hope for a comeback.
Sanchez, coming off a seamless four-touchdown, zero-interception performance last week at Notre Dame, took the blame.
"Last week I was the hero and this week I am a zero," said Sanchez, who passed for 277 yards and two touchdowns.
Sanchez's mistakes, however, were only a few of many.
USC failed to score after Oregon fumbled the opening kickoff, the Ducks stopping running back Joe McKnight on a fourth-and-one play at the 12-yard line.
An apparent 65-yard touchdown run by McKnight later in the quarter was nullified by a holding penalty on right tackle Drew Radovich, who was away from the play.
"We blew a lot of opportunities, man," said All-American left tackle Sam Baker, who left late in the third quarter because of a hip injury.
Despite their mistakes, the Trojans outgained Oregon, 378 yards to 339, and were in position to tie the score or take the lead at several junctures.
When they failed, Dixon made them pay with scrambles and timely throws out of the Ducks' no-huddle spread offense. The 6-foot-4 senior ran for 76 yards and a touchdown in 17 carries and completed 16 of 25 passes for 157 yards without an interception.
"We had guys covered and we weren't able to get him down as quickly as we needed to," Carroll said. "He was making eight and 10 yards instead of three and four. That was definitely the factor that kept the ball moving in this game -- his ability to get out and scramble."
USC trailed, 10-3, at halftime but tied the score on Sanchez's nine-yard touchdown pass to wide receiver Patrick Turner early in the third quarter.
But on the Trojans' next possession, fullback Stanley Havili fumbled and defensive end Will Tukuafu recovered for the Ducks at the USC 16-yard-line.
"Careless," Havili said. "I was very careless with the ball. I didn't have two hands on the rock and it came out."
Two plays later, running back Jonathan Stewart rumbled into the end zone for a 16-yard touchdown and a 17-10 Oregon lead.
On the Trojans' next series, Harper intercepted a pass intended for tight end Anthony McCoy and returned it 27 yards to the Oregon 42.
"A good read, and a physical mistake and just a bad throw," Sanchez said of the interception.
Stewart, who rushed for 103 yards in 25 carries, eventually scored again on a one-yard run for a 24-10 lead with 11:39 left.
Sanchez rallied USC late in the game by completing four of five passes during an 85-yard, five-play drive that he capped with a 14-yard touchdown pass to wide receiver David Ausberry.
The Trojans defense forced the Ducks to go three-and-out, setting up a final opportunity.
"Everybody was rolling," Turner said. "We felt like we were hitting on all cylinders moving down the field."
Starting at their 17, the Trojans advanced to Oregon's 33 with 26 seconds left.
On second down, Sanchez fired a pass for tight end Fred Davis in the middle of the field, but Harper intercepted it and returned it 34 yards.
"I acted like I was going to play the outside receiver, went inside and just made the play," Harper said.
Said Sanchez: "He must have read my eyes."
The Ducks ran out the clock and then celebrated amid frenzied fans who stormed the field.
USC players said they would regroup and move ahead.
"We've got four games left, it's not time to tank it," said senior nose tackle Sedrick Ellis, who had 12 tackles, including a sack.
Carroll said he would wait to make a determination about the quarterback situation for next week's game against Oregon State.
As for the Trojans' goal with four games left . . .
"It's get ready for next week and get yourself on track to get a win," Carroll said. "You just keep playing and see what happens at the end."
KEYS TO THE GAME
Gary Klein's keys to the game and how USC measured up:
1. Poised passers. USC's Mark Sanchez handled the Autzen Stadium crowd noise, but two of his passes were intercepted in the second half, one leading to an Oregon touchdown and the other clinching the Ducks' victory. Sanchez finished having completed 26 of 41 passes for 277 yards and two touchdowns. Oregon's Dennis Dixon coolly completed 16 of 25 passes for 157 yards and scrambled for 76 yards and a touchdown.
2. Got your back. Dixon and running back Jonathan Stewart, who rushed for 103 yards and two touchdowns in 25 carries, kept Trojans linebackers on their toes. Keith Rivers had 12 tackles, Rey Maualuga 11 and Brian Cushing eight. Oregon's linebackers helped limit USC to 101 yards rushing and tight end Fred Davis to only one catch for 11 yards.
3. Special teams. For the second week in a row, one of Greg Woidneck's punts hit an opposing player and the Trojans recovered the fumble and eventually scored a touchdown. David Buehler also kicked a 30-yard field goal. The Trojans failed to capitalize, though, after Andre Crenshaw fumbled the opening kickoff. Matt Evensen kicked a 41-yard field goal for the Ducks.