LAS VEGAS -- Isaac Hamilton scored 22 points as third-ranked UCLA beat USC 76-74 on Thursday night in a Pac-12 tournament quarterfinal game at the T-Mobile Arena.

The Bruins, seeded third in the tournament, play second-seeded and seventh-ranked Arizona in a semifinal game Friday. Top-seeded Oregon and fifth-seeded California meet in the other semifinal.

TJ Leaf added 14 points, six rebounds and five assists for UCLA (29-3), while Lonzo Ball had 12 points and seven assists.

"We just didn't make the shots we normally make, and we kind of got out of flow that way," said UCLA coach Steve Alford, referring to the Bruins shooting 41.2 percent from the field and committing 13 turnovers.

"But our guys did a really good job of making the plays they had to make, especially defensively."

USC, which is hopeful of an NCAA Tournament bid at 24-9, was led by Jordan McLaughlin's 18 points, Elijah Stewart's 17 points and Chimezie Metu's eight points and 14 rebounds.

"We have shown we can play with anybody," USC coach Andy Enfield said. "Five teams from the Pac-12 should make the tournament, including us and Cal (with UCLA, Oregon and Arizona the others)."

Stewart added: "I feel like 24 wins is kinda hard to leave us out, and we don't play at a low-division school."

Hamilton made a baseline jumper with 2:08 remaining to put UCLA ahead 74-69. After the teams traded possessions, Metu made two free throws with 1:05 left to cut the lead to 74-71.

Leaf missed a shot in the lane, and USC's Bennie Boatwright misfired on a 3-point try.

UCLA's Ike Anigbogu missed the front end of a one-and-one, giving USC another chance, but McLaughlin was unsuccessful on a running one-handed shot, and Stewart's put-back attempt was off.

Bryce Alford was fouled with 13 seconds left, and he made both free throws to put UCLA ahead 76-71. Boatwright's 3-pointer with six seconds remaining was USC's last gasp because the Trojans could not foul a player before time expired.

"This is probably a game we don't win back in January," Steve Alford said. "We didn't have too many tough shooting nights, and tonight was one of those. We were able to get enough stops."

UCLA took a 14-point lead with five minutes remaining in the first half after holding the Trojans scoreless for the first five minutes of the game.

USC scored the last eight points of the half over the final 2:07 to cut the deficit to 38-35. De'Anthony Melton converted a three-point play and Jonah Mathews made a 3-pointer in that span.

The Bruins led by many as 13 points in the second half, but the margin was cut to 69-64 with 5:31 remaining in regulation on an alley-oop dunk by Stewart off a pass by McLaughlin.

Stewart then made a layup and a 3-pointer on consecutive possessions to cut UCLA's advantage to 71-69 with 4:13 left.

"We came out slow, but at the end, we had them," Mathews said. "We both are good teams in the Pac-12, but we just didn't come out with the win tonight."

UCLA's inability to put away USC after building double-digit leads in the first and second halves was a case of the Bruins "not playing up to our abilities," according to Leaf.

"We know what kind of team we are," he added. "We just have to play how we know."

NOTES: USC has played eight games against teams ranked in the top seven in the country in terms of winning percentage -- UCLA three times, Oregon twice, Arizona twice and SMU. Their record in those games is 2-6. ... The Bruins led the nation in points per game (91.3) and assists per game (21.7) entering play Thursday. ... USC has seven games of 10 or more steals, and its 219 steals and 7.1 steals per game lead the Pac-12. G De'Anthony Melton's 60 steals entering the game were sixth nationally among freshmen. He added three more steals Thursday. ... The Bruins have made at least one 3-point attempt in each of their past 683 games. The last game UCLA played in which it didn't make a 3-pointer was against Stanford on Feb. 3, 2000.