Teondre Williams scored 16 to lead the Ducks (3-2), who lost their second straight and were never able to recover from a 30-20 halftime deficit.
EUGENE — Anthony Johnson scored 20 points and Brian Qvale added 15 points and 10 rebounds as Montana defeated Oregon 68-55 Monday night.
Michael Taylor also scored 12 for the Big Sky Conference's Grizzlies (4-0), who beat a Pac-10 team for the first time since an 88-69 win against Stanford in 2005.
"We just wanted to come out, be organized, be aggressive, just be the attacker," Qvale said. "They're a great team but our defense was working well."
Johnson scored most of his points from the foul line. The guard made 14 of his 15 free-throw attempts and was 3-of-6 from the field. Qvale, a 6-foot-11 junior, had his way inside, making seven of his eight shots. The Grizzlies shot 51 percent from the field overall, compared to 33 percent for Oregon.
Teondre Williams scored 16 to lead the Ducks (3-2), who lost their second straight and were never able to recover from a 30-20 halftime deficit. Oregon played without two injured starters, center Michael Dunigan (hip) and forward Joevan Catron (back).
"I feel like we're a team that's out of rhythm," Oregon coach Ernie Kent said. "We were really stagnant tonight."
The only time it was close in the second half was following a 9-1 run by Oregon that cut the Grizzlies' lead to 39-36 with 11:12 to play.
The Ducks had a chance to tie the game following a turnover, but Matt Humphrey missed a 3-point attempt. Montana scored the next eight points on a layup by Qvale and back-to-back 3-pointers by Taylor to go up 47-36.
"That was huge," Montana coach Wayne Tinkle said.
Montana finished the Ducks off at the line, scoring 15 of the final 17 points on free throws including Johnson's 8-for-8.
Oregon led 12-4 following a 3-pointer by Williams 6:20 into the first half. But the Ducks scored just eight points the rest of the half, missing all but three of their next 17 shots.
Montana got hot in the final minutes of the half, and a layup by Mathias Ward 3:20 before halftime gave the Grizzlies a 21-20 lead and sparked an 11-0 run going into the break.