Gary Payton II had 10 points and nine rebounds for Oregon State (11-4, 2-1 Pac-12), which shot 51.3 percent from the field. Olaf Schaftenaar added nine points while Victor Robbins chipped in eight points for the Beavers.

Rondae Hollis-Jefferson led Arizona (14-2, 2-1) with 14 points, including 10-of-13 shooting from the free-throw line, while T.J. McConnell added 13 points, six rebounds and six assists. The Wildcats shot 37.8 percent from the floor, including 4-of-17 from 3-point range.

The first half was all about defense, especially by Oregon State, which held Arizona to a season-low 26.1 percent shooting for the first 20 minutes, including 1-of-10 from 3-point range. Yet, the Beavers couldn't pull away, and a McConnell layup and two free throws by Hollis-Jefferson in the final 1:25 gave the Wildcats a 21-20 lead at the break.

It was still a three-point game in favor of Arizona with just under six minutes to play, but Oregon State went on a 9-2 run, capped by Malcolm Duvivier's three-point play with 1:33 to go, to take a four-point lead. Gabe York's 3-pointer with 1:09 on the clock pulled Arizona within one and Hollis-Jefferson tied it with 50 seconds to go, but Morris-Walker's layup with 26 seconds left put the Beavers ahead, and McConnell's floater in the closing seconds was off the mark.

GAME NOTEBOOK: The upset of a top 10 team was the first by Oregon State since it beat then-No. 3 Arizona in March 2000. … Oregon State F Daniel Gomis took an elbow to the mouth with 6:21 to play and went to the locker room for repairs. … The Wildcats had five turnovers, the fewest forced by the Beavers this season.