EUGENE, Ore. (AP) -- Oregon State receiver James Rodgers rounded the corner in the second overtime, looked up field and saw just one defender between himself and a go-ahead score.
"I knew he couldn't catch me," the freshman said. "I just homed in on a touchdown."
Rodgers dashed 25 yards for the score, and the Beavers defense stuffed Oregon (No. 17 BCS, No. 18 AP) on fourth down to preserve a 38-31 victory Saturday in the 111th Civil War.
"We knew it had to be a big play," Oregon State coach Mike Riley said of the eventual winning touchdown.
The two teams matched field goals in the first extra session before Rodgers broke free on the first play of the second overtime. Oregon (8-4, 5-4 Pac-10) was faced with fourth-and-1 from the 16 when it got its chance to answer, but tailback Jonathan Stewart was stopped on a run up the middle.
"That play should have been measured, but the officials ran off before it could be," Oregon coach Mike Bellotti said. "I'm not as fast as Joe Paterno. I couldn't catch them."
The Beavers (8-4, 6-3) wasted little time spilling onto the field to celebrate their victory, which gave a monumental lift to their bowl resume with a third straight win. It was the first time a road team had won the rivalry game since 1996.
Both teams had a chance to win in regulation with field goal attempts in the final minutes.
Oregon cornerback Walter Thurmond blocked a 35-yard field goal attempt by Oregon State's Alexis Serna with 1:09 left to play, and Ducks kicker Matt Evensen missed from 53 yards with 26 seconds on the clock.
"We were absolutely confident in Serna but we put him in a bad situation," Riley said. "That was the first time we've had a kick blocked like that in a long time."
Evensen got a second chance after the Beavers were flagged for a personal foul, but confusion over spiking the ball to stop the clock forced the Ducks to rush the field goal unit onto the field. His 40-yard attempt on the last play of regulation fell short.
"There was miscommunication on the sidelines," Bellotti said.
Serna set the Pac-10 record for consecutive extra points with 140, then got one more in overtime to push it to 141.
Stewart finished with 163 yards rushing and was one of the few bright spots late in the season for Oregon, which was in the national title picture after knocking off then-No. 4 Arizona State on Nov. 3.
But the Ducks lost star quarterback Dennis Dixon to a knee injury in a loss to Arizona, then were shut out by UCLA -- a shocking turn of events for an offense that had not been held under 24 points all season and eclipsed 50 four times.
Meanwhile, Oregon State finished the season on a roll, winning six of their last seven -- the only loss coming at Southern California.
Redshirt freshman Justin Roper took over at quarterback for Oregon midway through the first quarter, after Cody Kempt failed to move the offense. Roper finished 13-of-15 for 144 yards and two touchdowns with an interception, but lacked Dixon's elusiveness and creativity.
"It's kind of bittersweet," Roper said. "I'm glad I got to play and contribute, but a loss to Oregon State is the worst you can have."
Oregon State jumped on the reeling Ducks two plays into the game, when tailback Matt Sieverson raced 38 yards up the middle for a touchdown. That came after quarterback Lyle Moevao -- playing in place of injured Sean Canfield -- hit Anthony Brown on a 29-yard pass.
Sieverson, subbing for an injured Yvenson Bernard, finished with 141 yards on 27 carries.
Roper hit Jeffrey Maehl on a 31-yard touchdown later in the quarter, but Oregon State pushed back ahead on Clinton Polk's 1-yard run.
Derrick Doggett picked off Roper a few seconds into the second quarter, returning it 28 yards for a 21-7 lead. But Oregon tacked on two touchdowns late in the half -- a 3-yard pass from Roper to Garren Strong and Jarrius Byrd's fumble return for a touchdown.
Roper scored from 7 yards out to give the Ducks their only lead of the game, 28-21, with 7:10 left in the third quarter. But Moevao capped an 8-play, 71-yard drive with a 1-yard run a few seconds into the fourth quarter to tie it at 28.