Kyle Anderson's late putback proved to be the difference as No. 21 UCLA defeated 18th-ranked Arizona for the third time this season, taking a 66-64 victory to advance to the Pac-12 Championship game.
Jordan Adams was instrumental in the Bruins' (25-8) second double-digit comeback victory in as many days, scoring a game-high 24 points, however it did all end well for the star freshman.
He landed awkwardly on his right foot late in the contest, and after the game, x-rays revealed a break, which is expected to end his season.
Top-seeded UCLA will have to move on without him and will take on Oregon in Saturday's final.
Anderson finished with 10 points and five steals, while Shabazz Muhammad and Travis Wear each scored 11 in the victory.
Solomon Hill scored 10, but misfired on a potential tying bucket in the waning seconds for Arizona (25-7). Brandon Ashley scored a team-high 15 points off the bench in defeat.
"Well, it was obviously a great college basketball game," said Arizona coach Sean Miller. "I want to give complete and total credit to UCLA. They fought hard. They have tremendous talent. They're very well-coached, and they made huge plays."
UCLA trailed, 37-27, in the early moments of the second half, but Adams and Muhammad combined for a 9-0 run which got the Bruins within two with 8:21 to play.
Kevin Parrom added a pair of free throws following a Mark Lyons dunk to put the Wildcats back up six, but Adams responded with 11 straight points, with his acrobatic reverse layup knotting the score at 58-58 with just under four minutes left.
Muhammad then broke the deadlock with a pair of free throws to put UCLA up by two, but Ashley's jumper at the other end tied things back up.
After Wear sank a pair from the line, Kaleb Tarczewski was only able to split his pair from the charity stripe, keeping Arizona behind by one.
The Wildcats got a stop when they got the rebound off Muhammad's missed jumper, but Adams stole the ball from Lyons near halfcourt. He then drew a foul while driving towards the basket and calmly sank his 10th and 11th free throws of the contest to put the Bruins ahead by three with 1:13 left.
Grant Jerrett tied the contest back up with a 3-pointer from the top of the key, but Arizona couldn't get the board off Adams' ensuing 3-point miss, which set up Anderson for the decisive putback.
"I think we did a good job of keeping our composure," said Anderson. "The leaders on our team stressed to the five guys that are out there that we have to stay calm, being down 11 or 9 or whatever it was. I think that's what we did a really good job of and we were able to fight back for a second time and end up with the win."
Both teams were neck-and-neck through the first 13 1/2 minutes of play until Hill drained back-to-back three's to give Arizona a 26-18 lead and it held a 30-26 edge at the break.
The Bruins have won seven of their last eight ... Lyons scored 13 for Arizona, which was 7-for-17 from 3-point range ... The Bruins made just one 3-pointer on 12 attempts ... The Wildcats had 13 turnovers.