Darron Thomas threw four touchdown passes and No. 9 Oregon clinched a berth in the Pac-12 championship game with a 49-21 trouncing of visiting Oregon State in the annual “Civil War” game.

LaMichael James rushed for 141 yards before leaving with an elbow injury for the Ducks (10-2, 8-1 Pac-12 North), who will host UCLA in the inaugural conference title game this Friday.

Oregon rolled up 669 yards during its fourth straight victory over the Beavers (3-9, 3-6), who lost nine games in a season for the first time since 1996.

Thomas, who passed for 294 yards, threw three first-half touchdown passes as Oregon rebounded from last week’s loss to USC, a defeat that eliminated the Ducks from the national championship picture.

James departed after injuring his left elbow early in the third quarter. Earlier this season, he dislocated his right elbow.

Oregon took a 7-0 lead on a 1-yard run by James in the opening quarter and Oregon State struck back on Sean Mannion’s 58-yard touchdown pass to Jovan Stevenson with 11:08 left in the half.

The Ducks regained the lead three minutes later on a 16-yard pass from Darron Thomas to David Paulson. The lead was extended to 28-7 by halftime as Thomas tossed an 8-yard scoring pass to DeAnthony Thomas and a 16-yarder to Kenjon Barner.

Barner scored on a 1-yard run in the third quarter and Colt Lyerla caught a 39-yard scoring pass from Thomas early in the final quarter to make it 42-7.

Mannion threw three touchdown passes, including fourth-quarter scores to Kevin Cummings (19 yards) and Brandin Cooks (23). He was intercepted twice.