EUGENE, Ore. - Senior forward Elgin Cook scored 26 points as Oregon defeated No. 21 USC 89-81 on Thursday in a Pac-12 game at Matthew Knight Arena.

Forwards Dwayne Benjamin and Chris Boucher added 16 points apiece and forward Dillon Brooks scored 14 as the Ducks (15-4) improved to 4-2 in the conference.

Freshman forward Bennie Boatwright scored 23 points to pace the Trojans (15-4), who fell to 4-2 in the Pac-12.

Oregon led 46-41 at halftime and stretched the lead to 50-43 on a basket by Boucher. USC guard Julian Jacobs made a 3-pointer and Boatwright scored the next five points for the Trojans to cut the lead to 52-51.

Brooks answered with a jumper and a 3-pointer to give the Ducks a 57-51 lead. USC forward Nicola Jovanovic made two free throws and Boatwright added a jumper to get the Trojans within 58-55 before Oregon scored six straight points.

Cook scored and Brooks drove for a layup before Benjamin got a steal and layup to put the Ducks up 64-55 with 13:50 left. After Jovanovic made a free throw, forward Jordan Bell scored inside for Oregon and Cook added a 3-pointer to put the Ducks ahead 69-56 with11:57 left to play.

Bell added a basket and Brooks made a 3-pointer to put the Ducks ahead 74-58 with 8:47 left on the clock.

USC scored eight straight points to get within 74-66 before Cook made a free throw and Boucher added a bucket to put the Ducks up 77-66.

The Trojans took an early 12-6 lead on a jumper by Jacobs. After Oregon came back, USC took a 23-21 lead on a dunk by guard Elijah Stewart.

A 3-pointer by Boatwright put the Trojans up 26-21 with 10:22 remaining but the Ducks scored the next six points for a 27-26 lead with 8:45 left. The lead grew to 36-30 nearly four minutes later on 3-pointer by guard Casey Benson.

USC scored seven straight points and took a 37-36 lead on a basket by forward Darion Clark with 3:45 remaining. Oregon scored the next 10 points and held a 46-41 lead at halftime.

NOTES: The Trojans entered the Associated Press poll at No. 21 this week, their first ranking since Nov. 17, 2008. USC's 15-3 start to the season is its best since 1991-92. ... USC has four players with at least 32 three-pointers after having only three players with at least 16 three-pointers last season. ... The Ducks played their 100th game at Matthew Knight Arena.