The Wildcats routed the Buffaloes 88-61 for their first win in Boulder since 1973. They did it by holding Colorado without a bucket until 9:50 remained in the first half, then by shooting 84.6 percent in the second half.
"They whipped us tonight every which way you can whip a team," Colorado coach Tad Boyle said.
Freshman Aaron Gordon shook off a poor performance at Utah last week by scoring 21 of his season-best 23 points in the second half and Nick Johnson added 20 points for the Wildcats, who made 22 of 26 shots after halftime.
"We've had a few shootarounds here, we felt comfortable in their gym, it all just clicked for us," Johnson said.
It was a rare breather for the Wildcats (25-2, 12-2 Pac-12), who scrapped their way through a series of close games since beating Colorado by 12 in Tucson, Ariz., on Jan. 23, before close losses at Cal and archrival Arizona State dropped them from the top spot in the AP Top 25.
After that first game in Tempe, Buffaloes forward Xavier Johnson dissed the 'Cats, saying, "they're not that good." He also said that even without injured star Spencer Dinwiddie, the Buffaloes were the more talented team and he suggested the rematch in Boulder would be a blowout.
He was right, but it was the Wildcats who made this one a laugher, not the Buffaloes, who were throttled by Arizona's suffocating defense and their hot shooting hands.
"I don't think you have any of our players saying anything negative about Colorado, saying, 'We're going to win by 20,'" Arizona coach Sean Miller said. "We don't do that. For us, we have to play the right way. We have to compete hard. And certainly we respect Colorado."
Coming off an emotionally draining win over the Sun Devils on Wednesday night that burnished their NCAA tournament credentials, the Buffaloes (20-8, 9-6) came out ice cold, missing their first 14 shots.
They trailed 22-5 before Jaron Hopkins sank a 3-pointer from the left side 10:10 into the game.
That sparked a 16-4 run by Colorado—with seven points coming from the free throw line—to make it 26-21 and force an Arizona timeout. The Wildcats settled down thanks to a baseline drive by Rondae Hollis-Jefferson and a pull-up jumper by T.J. McConnell.
The only field goal by a Buffaloes starter before halftime came on Askia Booker's jumper with 2 seconds left in the first half.
After a horrendous start, however, the Buffaloes clawed their way back before Gordon sank three straight layups and Johnson's jumpers helped the Wildcats pull away.
In celebration of senior night, Boyle gave 7-foot center Ben Mills his first start of his career. He took the place of Josh Scott, who had started every game since Feb. 27, 2013, when he was dealing with a concussion.
Scott's absence was quickly felt as Colorado was outrebounded 6-1 and fell behind 8-1 before Scott replaced Mills 2:49 into the game. But the Buffaloes didn't turn things around right away, as the Wildcats built those advantages to 10-3 on the boards and 14-3 on the scoreboard by the 14:39 timeout.
Thanks to a 12-3 advantage at the stripe, however, the Buffs trailed just 31-25 at the half after shooting 6-for-27 from the floor.
Scott, who led the Buffs with 18 points, sank a jumper to open the second half that made it a four-point game, but the Buffs couldn't get any closer and the Wildcats began to pull away when Kaleb Tarczewski's 3-pointer made it 40-33.
"I think we got a little jump shot-happy, but I think that's a credit to them," Scott said. "I think we turned the ball over a couple of times at some key points in the game and it's mainly because they pack the paint."
About the only thing the crowd had to cheer about by the end was Mills' 3-pointer in the final minute, the first of his college career.
The 27-point loss was the biggest at home in the Boyle era, and he said it was particularly disconcerting with ESPN's College GameDay crew in town.
"Our fans were so ready for this game, for this win, and we gave them nothing," Boyle said. "That's a sick feeling to go home with and to live with. I haven't been embarrassed many times as a coach, but I was embarrassed tonight at the way our team played."
His players were, too.
"We're all embarrassed, man, really embarrassed," Booker said. "This is something that, whether we're on the road or at home, this should never happen again."
Follow AP Sports Writer Arnie Melendrez Stapleton on Twitter: http://twitter.com/arniestapleton