Nick Johnson totaled 18 points as No. 18 Arizona got past Colorado, 79-69, in Pac-12 quarterfinal action.
Mark Lyons hit key free throws down the stretch while posting 14 points, with Solomon Hill contributing 13 with seven rebounds for the fourth-seeded Wildcats (25-6), who will take on No. 1 seed UCLA in a Friday semifinal.
"We know they got us twice this season, so we are definitely looking forward to it," Johnson said. "I think this time we will play better defense against them. That got away from us in the middle of the season."
Spencer Dinwiddie had 18 points and Andre Roberson finished with 15 points and a game-best 11 boards for the Buffaloes (21-11), who had topped Oregon State in Wednesday's first round.
Colorado trailed 61-53 with just over six minutes left in the contest, but whittled its deficit to 68-64 as the clock ticked inside three minutes to play on a pair of Dinwiddie free throws.
Lyons countered with a triple to open up a seven-point Arizona edge, but Colorado's Askia Booker added a trey of his own and Roberson made two from the line to make it 71-69 with 1:03 to play.
But Johnson hit a layup for a four-point spread, and after Dinwiddie missed a layup, Lyons was sent to the line and connected on both his tries for a 75-69 game.
Booker bricked back-to-back shots from beyond the arc and Arizona's Grant Jerrett followed by making his two free shots, then Dinwiddie missed from long range and Lyons sank two more to salt away the victory.
"We're one of the top 37 teams (awaiting an at-large bid) in my mind," said Colorado head coach Tad Boyle. "But it's not for me to say."
An early 14-5 burst found the Wildcats ahead 22-13 after Brandon Ashley connected on two free throws.
Jeremy Adams made 1-of-2 from the line to finish an 8-3 burst that put the Buffaloes within 25-21, but Lyons drained a trey to kick-start an 8-2 clip that made it a 33-23 game after a layup from Angelo Chol.
The Wildcats went into the break up 39-28.
Jordin Mayes was good from beyond the arc as Arizona took a 54-40 advantage with just under 12 1/2 minutes left, before Colorado began to chip away.
Arizona shot 45.2 percent from the field to 43.1 percent for Colorado ... The Wildcats were 9-of-27 from 3-point range and the Buffaloes made 5-of-12 ... Jerrett led all players with four blocks.