Freshmen Ira Lee and Brandon Randolph also had impressive first-half dunks, while Ayton threw one down on a break in the second half for Arizona, which when not destroying the rim has been abysmal on offense.
The Beavers shot 39.3 percent overall but 42.9 percent from 3-point range.
Stephen Thompson Jr. chipped in 12 points for the Beavers.
The Beavers return to action against No. 11 Arizona State at 3 p.m. PT (4 p.m. MT) on Saturday at Wells Fargo Arena in Tempe.
However, the official scorer missed two points along the way, and Altman's appeal to the game officials went unheard until halftime when they put the points back on the board, although at first the statistics showed OR ahead 42-41. Nowell carried Washington in the first half with 11 points and he got help from his supporting cast in the final 20 minutes.
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Also Saturday morning, Port Authority police said they arrested a 61-year-old man with a stolen gun as he went through security. Frozen equipment, luggage-handling problems and staff shortages slowed down operations on the ground.
The Pac-12 won't have three top-10 teams as it did a year ago with Arizona, Oregon, and UCLA, but it without a doubt has the most parity in college basketball this season.
The next one almost brought the house down. The Beavers went back ahead 35-31 with its defense continuing to throw off UA offensively.
"I probably have some responsibility for that because I just didn't quite maybe manage possessions better with the lead and try and go a little bit longer with a possession and move the ball a little bit more", head coach Bobby Hurley said after the game.
The Wildcats took a 36-35 lead on a 3-pointer from Jackson-Cartwright with 10:25 left and pushed it to three points when Ayton crashed in for a fast-break layup.
It was back and forth after that until Ayton's rebound basket put Arizona ahead for good, 40-39 with 7:33 left. Washington is seventh nationally at 12-4 after going 9-22 a year ago. Gabby Green, a Cal transfer, led the Lions (11-5, 3-2) with 19 points. Its previous low was 63 in a victory over St. Louis.
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Carabinieri police said "dozens" of public administration officials were among the 169 people arrested. The BBC reports that the faction was plotting to expand into neighboring Switzerland.
Drew Eubanks added eight points, five rebound and two blocked shots.
Four players are averaging at least 15.0 points per game for OR, they are: Payton Pritchard (15.0), Elijah Brown (12.9), Troy Brown (12.3) and White (10.8).
The Wildcats fell behind right away, hitting just one of their first six shots while OSU took an early 12-2 lead.
Allonzo Trier scored 15 of his game-high 21 points in the second half to lead the Wildcats. Kodi Justice led Arizona State's team in scoring with 21 points, while shooting 50% from the field (making 6 of 12 attempts).
First, Allonzo Trier - who heated up in the second half and finished with 21 points - over Ethan Thompson.
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Thai police say he admitted to being a member of a Yakuza gang, but he did not confess to the 2003 murder that he was wanted for. He's implicated, along with seven others, in the killing of Kashihiko Otobe, who was the deputy leader of the rival Kamiya gang.