EUGENE, Ore. -- With one conference loss, Oregon coach Dana Altman was somewhat dire when he addressed the 13th-ranked Ducks before their game against No. 5 Arizona on Saturday.
"I told our guys this morning, I said, `Fellas, I'll be honest, we've got to win the game today or it's over,' And it would have been," Altman said about the tight Pac-12 Conference race.
It was clear the Ducks didn't want it to be over.
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Tyler Dorsey scored 23 points, including six 3-pointers, and Oregon snapped Arizona's 15-game winning streak with a decisive 85-58 victory Saturday.
Dillon Brooks added 18 points and four 3s as the Ducks (21-3, 10-1) extended their home winning streak to 40 games, an ongoing school record. Going into the game, it was the second-longest streak in the nation behind Kansas with 51, but the Jayhawks fell at home to Iowa State 92-89 in overtime earlier Saturday.
Oregon hit 16 3-pointers, most since opening Matthew Knight Arena in 2011.
"After I knocked down the first one, I just felt like I could keep rolling," Dorsey said.
Rawle Alkins had 16 points for the Wildcats (21-3, 10-1) in their worst loss under coach Sean Miller since they fell 99-69 to BYU on Dec. 28, 2009. It was the team's worst margin of defeat while ranked in the top five in school history.
Arizona's 15-game winning streak was the third-longest active streak in the nation.
Miller and the team held a lengthy closed-door meeting after the loss.
"I think a perspective is what's next. We're 21-3 and we're 10-1 in the Pac-12. We've played some great basketball, and the team we just got beat by has an identical record. They're also 21-3 and 10-1, and right now the season didn't end, it's not spring," he said.
The Ducks had been struggling, losing on the road to unranked Colorado last weekend then barely escaping Arizona State 71-70 on Thursday.
But they didn't have trouble against the Wildcats, leading by as many as 37 points.
"We were pumped up to play, coming off a close game against Arizona State, we knew we had to play a lot better," Brooks said.
Oregon's shots from the perimeter were falling early. Dorsey hit three consecutive 3-pointers to put the Ducks up 19-6 in the first half. Arizona scored five straight to quiet the crowd.
The Ducks pulled away with a 17-0 run that included a string of five straight 3-pointers. Casey Benson and Chris Boucher each hit 3s that put the Ducks up 27-11, then Benson added two more and Dorsey hit another to stretch the lead to 36-11 and put the crowd on its feet.
Arizona struggled from the field, going 7:03 without a basket. They were 0 for 11 from the field, making just two free throws as the Ducks built a 38-13 lead. The drought ended with Chance Comanche's dunk with 2:33 left.
Oregon, with 10 3-pointers, led 38-18 at the half.
Brooks' decisive dunk gave Oregon a 49-26 lead with 15:52 left and Arizona never threatened.
Arizona was coming off a 71-54 victory over Oregon State on Thursday. The Wildcats' two previous losses this season came to Butler and then-No. 8 Gonzaga on Dec. 3. Arizona defeated then-No. 3 UCLA 96-85 on Jan. 21.
It is the first time that teams ranked within the top 15 have met at Matthew Knight Arena since it opened for the conference season in 2011.
Arizona was the last team to beat the Ducks at home back in January 2015.
Arizona shot just 25.8 percent from the field in the first half for its lowest first-half point total of the season. The previous low was against Gonzaga, when the Wildcats trialed 38-26 and shot 35.7 percent.
Oregon and Arizona are now knotted atop the Pac-12 standings with seven games left. The Ducks will likely move into the Top 10 as a result of the victory, but they'll face a big challenge right away on Thursday against No. 11 UCLA at Pauley Pavilion. The Ducks were ranked as high as No. 4 early this season, but dropped after losses at Baylor (Nov. 15) and to Georgetown in Maui (Nov. 21)
Arizona: The Wildcats host Stanford on Wednesday.
"This game is over with and we're done with it," Arizona guard Kadeem Allen said. "We'll leave this trip in Oregon and go back to Tucson tonight, and from there it's a bounce-back game against Stanford."