Arizona avenged a one-point loss in Boulder last month with a 71-57 victory over Colorado in front of 14,225 hostile witnesses at the McKale Center.
The Buffs (16-8, 8-4) failed to make a statement to the NCAA Tournament selection committee on national television after falling to 1-4 on the road in Pac-12 play.
That doesn't mean Tad Boyle's dream of hanging a conference championship banner at the Coors Events Center is dashed.
There's just more company in the jumbled race and an even greater sense of urgency for CU.
"We have a very, very small margin of error now as we move forward in this league race," Boyle said. "We're still in it. Now we're tied with Arizona. The schedule doesn't favor us, but I think we have some winnable road games.We have to take care of business and get them."
CU acted like a team that meant business coming out of the halftime locker room. Andre Roberson, who led the Buffs with 12 points and 11 rebounds, threw down a pair of dunks as the visitors tied the score 36-36.
But the Wildcats (17-8, 8-4) counter-punched with a 12-3 run to take a 51-42 lead with 8:29 remaining. CU never got any closer than seven points after that.
"Down the stretch, I thought we just kind of fell apart," said Roberson, who also had three blocks, two assists and one steal in 29 minutes. "We weren't executing as much and took some bad shots. But we fought hard as a team."
Austin Dufault scored three straight times in the paint to keep the Buffs within striking distance. It wasn't nearly enough to counter Jesse Perry (17 points, 11 rebounds) and Solomon Hill (16 points, 14 rebounds) on the other end.
The dynamic inside duo had eight offensive rebounds. Perry and Hill each stuck in a dagger late after CU didn't block them out.
"I thought that was the key to the game was Perry and Hill getting offensive rebounds and scoring the ball in the second half," Boyle lamented. "You have to finish off those defensive possessions."
CU trailed 34-28 at halftime after suffering through a 9:03 drought without a made field goal.
The Buffs got off to a strong start and led 16-11 after a transition basket by Carlon Brown.
A 3-pointer by Hill sparked a quick 11-2 response by Arizona. A three-point play by Spencer Dinwiddie hushed the crowd and brought CU to within 22-21 with 9:53 to play in the first half.
"I think that the first four minutes of the first half, and the first five minutes of the second half, we saw Colorado play as fast as we've ever seen them play," Arizona head coach Sean Miller said. "If they can keep that up, then they will be extremely difficult to beat down the line."
The Buffs couldn't keep up the pace, shooting just 35.3 percent from the field in the second half and 37.3 percent for the game.
"Couldn't execute, couldn't get rebounds, couldn't get stops like we do at home," is how Brown summed up the lost opportunity.
The Wildcats also had trouble creating offense against the Pac-12's top field-goal percentage defense. Nick Johnson's 3-pointer with 3:28 left before the intermission was Arizona's first made basket in 7:19.
Hill, who highlighted the halftime stat sheet with 13 points on 5-for-6 shooting, capped a 10-2 run to give the home team a 32-23 cushion.
A 3-pointer by Nate Tomlinson just before the buzzer cut the CU deficit to six points.
There were five ties and three lead changes in the first half. Both teams shot 40 percent from the field.
"I'll never question our team's heart. I think we have a real tough group of guys," Dufault said after finishing with 10 points and seven rebounds. "Execution at both ends of the floor is what really hurt us. Toughness and all that stuff ... I think we showed up to play, we just didn't execute."
CU missed out on a chance to get off to the program's best start to a conference season through 13 games since the 1966-67 season (10-3).
As the Buffs took the bus to Tempe, where they will look for a split against Arizona State on Saturday, they received some good news in the standings.
Oregon (17-7, 8-4) joined Arizona and CU in a three-way tie for third place with a victory over Washington. The Huskies (16-8, 9-3) are now tied for first with Cal (19-6, 9-3) after the Bears' road win at USC.
"I feel like we can go out there and beat everybody that is ahead of us," Roberson said. "If we take care of the games at home and compete in the road, we'll be all right as far as winning the Pac-12."