CORVALLIS — So much for the greatest team ever.

CORVALLIS — So much for the greatest team ever.

Likewise for the best team of the Pete Carroll era.

Top-ranked USC looked anything but the part Thursday night, falling behind Oregon State by three touchdowns in the first half then rallying before falling short in a 27-21 defeat that put a serious crimp in the Trojans national championship plans.

A delirious crowd of 42,839 at Reser Stadium and a national television audience watched Oregon State upset the Trojans here for the second time in three years.

"We weren't ready to do what we needed to do," Carroll said. "We felt like we had great preparation, we thought we did everything like we needed to and then when we're out there it just didn't feel like it."

USC (2-1) was thought to have a mostly clear path to the Bowl Championship Series title game after dispatching Virginia and Ohio State. Pac-10 Conference teams were not expected to derail the Trojans, not after four of them lost to Mountain West Conference teams in one weekend.

But Oregon State manhandled the Trojans for nearly the entire game and rode the relentless running of freshman running back Jacquizz Rodgers to victory.

"People that don't think that Pac-10 teams are going to play like this — they're gonna," Carroll said. "This is the way it is. This is reality."

The Beavers shut down USC's offense for most of the game and pushed around a defense that came in surrendering a nation-low five points a game.

"They just beat us up, plain and simple," USC fullback Stanley Havili said.

USC, however, still had a chance to win in the final minutes.

After struggling to elude pressure throughout the first two quarters, quarterback Mark Sanchez came out firing and quickly pulled the Trojans to within seven points with a 26-yard touchdown pass to Ronald Johnson and 29-yard strike to Damian Williams.

When Clay Matthews blocked a field-goal attempt in the fourth quarter, the Trojans looked primed to come back.

But USC failed to capitalize and gave the ball up on downs.

The Trojans got the ball back at their 2-yard line with 3:15 left, but Greg Laybourn intercepted a pass and returned it 28 yards to the 2, setting up a Rodgers touchdown that made the score 27-14.

"I could have made the play," said Sanchez, who completed 18 of 29 passes for 227 yards and three touchdowns. "I'm ... kind of getting hit, but that's the way this game goes. I've completed plenty of passes when I've been under pressure like that."

After USC's final TD, Oregon State recovered an onside kick and ran out the clock.

"For some reason, we just knew," Oregon State safety Al Afalava said. "We felt that we would do it again."

Oregon State Coach Mike Riley was proud of his team that had been routed earlier in the season by Penn State.

"They learned from that," Riley said. "Every game is about competing and competition, and they came out and played."

Most of the Trojans credited Rodgers.

"He ran the ball hard; he ran the ball with a lot of heart," said safety Taylor Mays, who was forced to leave the game with a chest injury. "He was not intimidated. He wasn't scared at all."