LAS VEGAS -- Arizona guard Nick Johnson scored 18 points and the Wildcats weathered a furious Colorado rally in the second half to beat the Buffaloes 79-69 Thursday in a Pac-12 tournament quarterfinal game.
The Wildcats (25-6) will play UCLA (24-8) in a Pac-12 Tournament semifinal game Friday at the MGM Grand Garden Arena. Colorado (21-11) will await its fate Sunday for the NCAA tournament.
Johnson, a sophomore guard, ended his personal slump against Colorado by making six of seven field goal attempts, including both attempts from three-point range. In his five previous games against the Buffaloes, Johnson made only 9-of-28 field goals, 4-of-22 from three-point range.
Arizona led by as many as 14 points in the second half but Colorado trimmed the lead to 71-69 with 1:02 left behind Spencer Dinwiddie's 13 points after intermission at that point.
Johnson made a driving layup with 34.6 seconds remaining to put Arizona ahead 73-69. Colorado's Andre Roberson missed on an aggressive move to the basket on the other end and was whistled for a foul on the rebound.
Arizona's Mark Lyons converted two free throws to put Arizona ahead 75-69 with 23.6 seconds left. After Johnson blocked a three-point attempt by Askia Booker, Arizona's Grant Jerrett corralled the rebound following another Booker missed three-pointer.
Jerrett was fouled and made two free throws to seal the game for Arizona.
A factor in the game was Colorado freshman center Josh Scott whistled for his second foul at the 14:53 mark in the first half and Arizona ahead 11-8.
Scott's backup, Shane Harris-Tunks, had his legs tangled with Arizona's Grant Jerrett, fell hard to the floor and had to be replaced by 6-foot-4 guard Sabatino Chen with 12:45 left. That meant Colorado went with a small lineup of four guards and power forward Andre Roberson.
Arizona attacked the lane and outscored Colorado 9-4 in that stretch to build a 22-15 lead by the time Scott returned with 10:14 left. Scott played only seven minutes in the first half. The Buffaloes managed to cut the lead to 25-21 with 4:28 left in the half but Arizona made the next two baskets and ultimately led 39-28 at halftime.
Scott's foul trouble and Arizona's perimeter defense was difficult for the Buffaloes to overcome by the half. Colorado was 19-of-38 from three-point in the two regular-season meetings between the teams but attempted only two from beyond the arc, making one, in the first half.
With Colorado lacking an inside presence, Arizona attacked the basket and drew fouls. The Buffaloes had four players with two fouls each at the half.
NOTES: Colorado entered the game with a 3-2 edge over Arizona since joining the Pac-12 last season. The Buffaloes are 10-6 against the Wildcats overall, but 12 of those meetings were before 1975. ... Colorado was 5-0 in the Pac-12 tournament having won the title in four games last season and the opener this season against Oregon State on Wednesday. ... Colorado practiced at the MGM Grand Garden Arena on Tuesday and played the Beavers on Wednesday. Arizona had not stepped into the arena until 30 minutes before Thursday's game.