CORVALLIS, Ore. -- Nick Johnson said the Oregon State crowd got into the game during the second half and affected his Arizona team.
So he kept shooting.
"I felt pretty good shooting the ball over the past few games, so I just tried to stay with it. Especially in tough environments like this, I try to take over a little bit," Johnson said.
Kaleb Tarczewski added 12 points and nine rebounds for the Wildcats (28-2, 15-2 Pac-12), who had already clinched the regular-season conference title. The Wildcats have won five straight with their last loss on Feb. 14 at archrival Arizona State.
"We want to finish this season out as strong as possible. We don't want to take an 'L,' not play hard, because, I mean, that carries over to the next game," Johnson said. "We have ourselves a little momentum going here."
Roberto Nelson scored 25 points and Devon Collier had 14 points and 11 rebounds for the Beavers (15-14, 7-10).
Arizona built several leads during the game but couldn't pull far away from a feisty Oregon State team.
Arizona opened the game on a 7-0 run before Oregon State responded and took a 10-9 lead on a steal and layup by Hallice Cooke at the 14:13 mark.
The Wildcats gradually crept away, and an alley-oop from T.J. McConnell to Johnson for a dunk put the Wildcats up 31-22 with 3:53 left in the half, their largest lead of the game. Arizona led 36-33 at halftime.
The Beavers went ahead 46-44 after consecutive 3-pointers by Cooke, the latter at the 15:15 mark.
Arizona went on a 7-0 run that ended with a jumper by Johnson that made it 58-51 with about 10 minutes left, but Oregon State again responded, tying the game at 58 on a layup by Eric Moreland with 8:13 left.
The Wildcats forced turnovers on three straight possessions and took a 69-64 lead with 1:36 left. With 30 seconds left and the score the same, Rondae Hollis-Jefferson blocked a shot by Cooke. Hollis-Jefferson finished with 13 points and six boards.
Oregon State outrebounded Arizona 43-34, only the sixth time Arizona has lost the rebounding battle this season.
"No team in the 30 games we have played has punished us on the glass like Oregon State did," Wildcats coach Sean Miller said.
"I would put their physicality, their size, against any front line in the country. To be outrebounded on the road and still win, we'll take it," he added.
The Wildcats crushed the Beavers on the boards 39-24 in the teams' last meeting on Feb. 9, which host Arizona won 76-54.
The Wildcats forced 17 turnovers and committed only eight.
"You play the game with eight turnovers, you're always going to be in it," Miller said.
Collier said the turnovers cost Oregon State the game.
"We minimize them and we win most of our games. We've just got to protect the ball more," he said.
"You can't beat a team that's that good, that's that highly ranked without doing most of the things right," Beavers coach Craig Robinson said. "You can get away with making some mistakes but you can't make too many mistakes against a team like that. They're just too good."
Arizona won its 108th game in the past four years, the best four-year stretch in school history.
Oregon State hasn't beaten a top-five team since it upset No. 3 Arizona 70-69 in Corvallis in 2000. It hasn't beat a top-25 team in more than three years.
Nelson came into the game leading the Beavers with a 20.6-point average. He is on pace to become the first Oregon State player to lead the conference in scoring since Gary Payton in 1990.
Cooke, a freshman point guard, who was 7 for 31 from the field in his previous four games, finished with 10 points on 4-of-7 shooting.