Isaiah Newell scored on two fourth-quarter touchdown runs -- his only carries of the game -- as host No. 21 Oregon State rallied from a 21-point, second-half deficit to defeat No. 9 Oregon 38-34 Saturday afternoon in Corvallis, Ore., preventing the rival Ducks from clinching a berth in the Pac-12 Conference championship game.

Damien Martinez had his sixth consecutive 100-yard rushing game, gaining 103 yards before leaving with an apparent leg injury for the Beavers (9-3, 6-3 Pac-12), who clinched their first nine-win regular season since 2012.

A hobbled Bo Nix completed 27 of 41 passes for 327 yards and two touchdowns for Oregon (9-3, 7-2).

The Ducks were 0-for-5 on fourth-down attempts, with three of those coming in the fourth quarter.

Leading 34-31 with 9:39 remaining, the Ducks went for it on fourth-and-1 from their own 29-yard line. Nix was stopped for a 1-yard loss on a keeper.

Oregon State took advantage, with Newell scoring on a 6-yard run with 8:11 left to give the Beavers their first lead of the second half.

The Ducks marched to Oregon State's 3-yard line with three minutes left, but Nix's fourth-down pass for Troy Franklin fell incomplete and the Beavers ran out the clock.

Ben Gulbranson, who started his seventh straight game at quarterback with Chance Nolan sidelined by a neck injury, completed just 6 of 13 passes for 60 yards with two interceptions.

But Gulbranson scored on a pair of 1-yard runs, the latter with 12:31 remaining, to pull the Beavers within 34-31.

Nix threw a 9-yard scoring strike to Franklin with 14 seconds remaining in the second quarter to give the Ducks a 14-10 lead following a back-and-forth half, sparking a run of 24 unanswered points.

The Ducks seemed to pull away in the third quarter on short touchdown runs by Jordan James and Noah Whittington.

Camden Lewis added a 42-yard field goal to give the Ducks a 31-10 lead with 4:46 left in the third quarter.

The Beavers rallied -- entirely on the ground.

Oregon State got a 4-yard TD run from Deshaun Fenwick to stop the Ducks' run before Lewis kicked a 24-yarder to make it 34-17 with 14:57 to go.

Newell scored on a 15-yard run and the Beavers got the ball back on Oregon's 2-yard line after Ducks punter Alex Bales bobbled a snap. That set up Gulbranson's second TD.

--Field Level Media