EUGENE, Ore. -- Jordan Williamson hit a 37-yard field goal in overtime and Stanford (No. 13 BCS, No. 14 AP) upset Oregon (No. 2 BCS, No. 1 AP) 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 USC (No. 18 BCS, No. 21 AP) 38-28 earlier in the day to claim the Pac-12 South. Oregon (10-1, 7-1) will play Oregon State (No. 16 BCS, No. 15 AP) in the annual Civil War rivalry game in Corvallis.

The loss snapped a 13-game winning streak for the Ducks, 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 Kansas State's (No. 1 BCS, No. 2 AP) -- 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.

Oddsmaker Danny Sheridan told ESPN.com's Darren Rovell that, at this point, Notre Dame would be a 10-point underdog to the Crimson Tide.

Oregon was the only Pac-12 team that Stanford hadn't defeated over the past two seasons. But the Cardinal's tough defense 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.