The Ducks (20-5, 9-3 Pac-12) had dropped three of four, losing their grasp on sole possession of first place in the conference. They regained it for at least for 24 hours, moving a half-game ahead of Oregon and UCLA, who both play on Thursday night.
Oregon played its sixth straight game without Dominic Artis, out with a foot injury. The Ducks continued to stumble offensively without their starting point guard, but their defensive effort was enough to hand Washington its seventh loss in eight games. It was the first time Oregon has swept Washington in the regular season since 1995.
Abdul Gaddy led Washington (13-12, 5-7) with 17 points.
Oregon got a scare it didn't need when Loyd was fouled jumping for pass with 1:36 left. As he came down his left knee buckled and he stayed down on the floor for about a minute before walking very slowly to the Ducks' bench. He eventually walked off the floor at the end of the game on his own with only a slight limp.
The victory gave the Ducks 20 victories for the 14th time in school history. It would have come sooner if Oregon hadn't stumbled with consecutive road losses at Stanford and California, followed by a home loss to Colorado. Oregon got back on track by beating Utah at home last Saturday and then followed up by extending Washington's slide.
Arsalan Kazemi and E.J. Singler both finished with 11 points and Carlos Emory added 10 for the Ducks.
Washington leading scorer C.J. Wilcox continued to struggle. He missed his first six shots and finished 3 of 13 for nine points. Wilcox has been bothered by a foot problem that has limited his practice time. Washington shot just 35 percent and its 52 points tied for the third-fewest in a game during Lorenzo Romar's tenure as coach.
Washington closed to 35-32 in the opening stages of the second half before Oregon went on an 11-2 run. The Ducks scored six straight points, including a pair of baskets by Kazemi. Shawn Kemp Jr.'s follow dunk briefly stemmed the run, but the Ducks scored the next five to take their biggest lead of the game to that point. Oregon stretched the advantage to 44-34 with 13:14 left after Kazemi made one of two free throws. Loyd then stole a lazy inbounds pass by Wilcox and raced the other way for a layup, and the lead was 12 with 12 minutes left.
Washington tried to make another charge with six straight points of its own, but Tony Woods followed Loyd's wild layup attempt with an emphatic dunk just before the shot clock expired to push the lead back to 48-40 with 7:37 left. The teams traded empty possessions and Loyd hit a wide-open 3 for an 11-point lead with 6:47 remaining.
That proved to be enough. Washington trimmed the deficit to seven and had a chance to get closer, but Aziz N'Diaye missed the front end of a one-and-one. Loyd then hit a jumper at the top of the key and Dotson scored on a fast break to push the lead back to 11.
The loss was Washington's largest in conference play and continued a surprising slide after beginning the Pac-12 season 4-0.