OR opened an eight-point lead after breaking a tie at 58 with nine minutes left and held on.
The Beavers (10-6, 2-2 Pac-12) started the game on fire, jumping out to a 12-2 lead, as four of the five starters scored.
News 4 Tucson at 10 p.m. will have complete highlights and updates. Now it's time to see how they respond with a pair of hard games this week: At USC on Wednesday and at UCLA on Saturday.
As teams look to make their move in the Pac-12 Conference, the Ducks are not where they want to be following a loss to Oregon State and a 1-2 Conference mark. He was 6-of-12 with four 3-pointers for 21 points.
For the most part, they played strong perimeter defense in a zone that kept the pace slow while constantly having success using dribble penetration on the other end.
After Sunday's home game against Arizona, the Beavers get No. 8 OR in a home-and-home battle next weekend. ASU, however, lacks the required crisp rotations and the Ducks kept punishing them for it.
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OR had a 38-31 rebounding advantage and grabbed 15 offensive rebounds to Arizona State's eight.
Still, the Beavers had done enough to impress the NCAA tournament selection committee and were awarded an at-large berth to the tournament for the first time since the 1995-96 season. "They came in and worked their butts off (Tuesday) and they want to get better".
OR (12-5, 2-2 Pac-12) used a late spurt to go up eight points and hit four free throws in the final 32 seconds against the Sun Devils (13-3, 1-3).
The Sun Devils don't have an answer physically for players like McIntosh, who kept OR in a game that it, quite frankly, didn't deserve to be in with some of its sloppy plays early on.
Allonzo Trier scored 15 of his 21 points in the second half and the Wildcats, coming off a road loss at Colorado, pulled away from a sluggish, close game in the final 7½ minutes to beat the Beavers 62-53.
"They're really doing a great job and scoring inside and out", he said.