Spencer Dinwiddie scored a career-high 29 points and Andre Roberson added 15, helping Colorado hold off Colorado State 70-61 on Wednesday night.
Buoyed by a big first half, the Buffaloes (7-1) bounced back from their loss over the weekend to Wyoming, which dropped CU out of the AP poll.
Roberson added 14 rebounds.
The Buffaloes played in front of a Coors Events Center-record crowd of 11,708, and the noise clearly agitated the Rams (6-1) early as they trailed by 25 points in the opening half.
Colton Iverson scored 15 of his 19 points in the second half and grabbed 14 rebounds. Dorian Green added 18 points as the Rams fell a win shy of their best start in school history. They also were on the cusp of possibly appearing in the AP poll, something that hasn't happened since 1954.
CSU cut into the Buffs' big lead and whittled it to three with 6:43 to play, but two costly turnovers and layups from Askia Booker and Josh Scott helped send Colorado to the win.
However, Colorado didn't make it easy, as it struggled from the free-throw line, hitting just 7 of 14 over the final 1:33. But the Rams couldn't take advantage.
Playing an entertaining brand of hoops and coming off an appearance in the NCAA tournament, the Buffs have been in high demand around town. Season-ticket sales are up nearly 60 percent.
This was the 12th sellout under coach Tad Boyle, who has put the program back on the basketball landscape.
The deafening roar from the crowd certainly revved up the Buffaloes, who jumped out to a 15-2 lead.
As his team struggled early, CSU first-year coach Larry Eustachy looked nearly exasperated on the sideline. He's now 1-5 all-time against Colorado at Coors Events Center, with most of those games coming when he was in charge at Iowa State.
Colorado also was motivated by watching the Rams storm the floor after a 65-64 win last season in Fort Collins. It was a sight the Buffs didn't want repeated, especially on their home floor.
The Buffs led 42-22 at halftime. It was the highest first-half output for the Buffs this season, and the lowest for CSU.