Josh Scott scored a season-high 26 points and
George King scored 14 points and Josh Fortune had 13 for the Buffaloes (20-9, 9-7
Colorado secured its ninth 20-victory season.
Ryan Anderson had 19 points for the Wildcats, who had won six games in a row. Allonzo Trier scored 15 points.
Colorado led, 75-72, with 26 seconds left when Scott lost the ball driving in traffic. Arizona turned the ball back over, but then with nine seconds left, Scott was called for traveling.
Trier put up a three-point shot at the buzzer but hit the back of the rim and bounced off.
After leading by four points at the end of the first half, the Buffaloes moved in front, 56-45, after Scott converted a three-point play with 14:21 left. Arizona responded with a 9-3 but Colorado leaned on driving layups by Scott to stay in front.
A basket by Kaleb Tarczewski and a three-point basket by Gabe York cut the Colorado lead to 75-70 with 2:10 remaining.
at No. 13
Chris Boucher had 18 points and 13 rebounds, and Dillon Brooks had 17 points for the Ducks, who regained sole possession of the Pac-12 lead with three games remaining.