EUGENE, Ore. -- Jordan Williamson hit a 37-yard field goal in overtime and No. 14 Stanford upset No. 2 Oregon 17-14, denying the Ducks a chance to clinch the Pac-12 North and derailing their straight shot at the BCS title game.
If both Stanford and Oregon win in their final games next weekend, both will finish with one conference loss, which means Stanford will win the head-to-head matchup and go to the Pac-12 championship for a chance to play in the Rose Bowl.
After winning its fifth straight, Stanford (9-2, 7-1) will play its finale at No. 17 UCLA, which defeated No. 21 USC 38-28 earlier in the day to claim the Pac-12 South. Oregon (10-1, 7-1) will play Oregon State in the annual Civil War rivalry game in Corvallis.
The loss snapped a 13-game winning streak for the Ducks, which was the longest in the nation coming into Saturday.
"It hurts and as I told them, you'd like to have some words that would take the pain out of it, but there aren't," Oregon coach Chip Kelly said. "We'll feel bad for a little bit of time and we'll bounce back from it."
Oregon's loss, coupled with No. 2 Kansas State's -- they were also the top two teams in the BCS standings -- means third-ranked Notre Dame is now the lone unbeaten team in the race for the BCS title game.
The Fighting Irish control their national championship run, with No. 4 Alabama and a couple of other Southeastern Conference teams also in the thick of it.
Oregon was the only Pac-12 team that Stanford hadn't defeated over the past two seasons. But the Cardinal's tough defence smothered the highest scoring team in the nation.
Alejandro Maldonado missed a 41-yard field goal for the Ducks to open overtime before Williamson's game winner.
Redshirt freshman Kevin Hogan threw for 211 yards and a game-tying fourth-quarter touchdown for Stanford, while Stepfan Taylor rushed for 161 yards on 33 carries.
Down 14-7, Stanford went for it on fourth-and-1 on the Oregon 12 with 2:17 left in regulation and Ryan Hewitt ran two yards for the first down. Hogan hit Zach Ertz with a 10-yard scoring pass to tie it at 14 with 1:35 to go. Ertz fought to gain control of the ball with a defender as he fell to the turf on top of a Ducks player. The play was initially ruled incomplete, but a video review overturned it for the game-tying touchdown.
Despite a pass interference call that gave them a crucial first down, the Ducks were forced to punt on the ensuing series and Stanford took over with 36 seconds to go and the game went to overtime.
The Cardinal had the nation's best run defence going into the game, allowing an average of just 54.8 yards a game. Oregon, meanwhile, had the country's third-best rushing offence, averaging 325 yards a game.
Stanford held Ducks running back Kenjon Barner, who was averaging 136 yards rushing a game, to just 66 yards. Overall, the Ducks managed only 198 yards on the ground.
Oregon's top rusher was quarterback Marcus Mariota, who ran for 89 yards. Mariota, a redshirt freshman who had been getting Heisman buzz, threw for 207 yards and a touchdown.
Stanford stuffed what appeared to be a sure first-quarter Oregon touchdown drive when Mariota took off on a 77-yard keeper to the Stanford 15. But the Ducks couldn't get much closer, and Stanford got the stop when Oregon went for it on fourth-and-2 on the Cardinal 7.
Stanford scored first on Hogan's 1-yard plow into the end zone early in the second quarter.
Oregon tried again on fourth-and-4 midway through the quarter, but was unsuccessful, this time when Mariota's pass to tight end Colt Lyerla fell incomplete.
When Oregon took over on downs from Stanford on the next series, the Ducks marched 59 yards in three plays -- capped by Mariota's 28-yard touchdown pass to Keanon Lowe -- to tie it at 7-all.
Oregon extended its lead to 14-7 on De'Anthony Thomas' 6-yard scoring run in the third quarter, but missed a chance when Maldonado's 42-yard field goal attempt went wide right.
Williamson missed a 43-yard field goal attempt for Stanford early in the fourth quarter.
The victory for Stanford is retribution for Oregon's dominance over the Cardinal for the past two seasons.
Last year, Stanford was ranked No. 3 and looking toward its own national championship bid with quarterback Andrew Luck when then-No. 6 Oregon visited Palo Alto and emerged with a 53-30 victory. Running back LaMichael James, who would join Luck's NFL draft class in the spring, ran for 146 yards and three touchdowns.
The year before, Oregon defeated the Cardinal and Luck 52-31 in an early October hurdle en route to an undefeated regular season and an appearance in the BCS title game against Auburn.
In both seasons, Oregon went on to win the conference titles. The Ducks have won three straight Pac-12 championships.
The Ducks went into the game hurting on defence after a 59-17 victory over California last weekend.
Oregon was without free safety Avery Patterson seriously injured his left knee in the second quarter and is believed to be out for the rest of the season. Patterson had taken over as starter for senior John Boyett, whose career at Oregon ended earlier this season when he needed surgery on both knees. Starting nose guard Wade Keliikipi did not play.
Because the Ducks do not disclose injuries, there was also uncertainty about the secondary, leading to speculation that the team might use Lowe or even multi-purpose sophomore back Thomas on defence. But they did not.