In UCLA’s first game without its most relentless defender, it got an offensive barrage from its star freshman guard to ward off a huge upset.

Bailey’s career-high 26 points pushed the second-ranked and top-seeded Bruins to an 80-69 victory over ninth-seeded Colorado on Thursday afternoon in a Pac-12 tournament quarterfinal at T-Mobile Arena.

UCLA could exhale only after a sequence in which Jaime Jaquez Jr. followed a steal with a give-and-go with Tyger Campbell that ended in a Jaquez layup in which he was fouled and made the free throw, extending the Bruins’ lead to 73-65 with 1:21 left.

Frustrations then boiled over for Colorado Tad Boyle, who picked up two technical fouls and was ejected with 54 seconds left.

Campbell finished with 18 points and seven assists and Jaquez tallied 16 points and nine rebounds for the Bruins (28-4), who extended their winning streak to 11 games.

UCLA guard Jaime Jaquez Jr., left, looks to pass around Colorado guard Luke O’Brien during the first half Thursday. Jaquez finished with 16 points.

(David Becker / Associated Press)

Clark was out after suffering a lower-leg injury against Arizona last weekend that could keep him out of the postseason. He did not travel with the team to Las Vegas.

Tristan da Silva scored 17 points for the Buffaloes, who were also shorthanded with point guard K.J. Simpson sidelined by mono.

The Bruins were in trouble early in the second half when UCLA coach Mick Cronin yanked Jaquez after the Pac-12 player of the year committed back-to-back turnovers. The Buffaloes had a counter for every UCLA push and kept making shots, taking a 49-46 lead on a corner three-pointer from Luke O’Brien.

Da Silva gave Colorado a 61-60 lead with a three-pointer over Jaquez before Jaquez countered with his own three-pointer, sparking a 9-0 push for the Bruins that included a Campbell layup in transition and two Bailey free throws.

UCLA trailed, 38-37, at halftime after Colorado continually made itself comfortable behind the three-point line, making seven of 12 shots from long range.

The Bruins got an early boost from Bailey, who scored 12 points over the first 11½ minutes before picking up his second foul and going to the bench for the remainder of the first half.