UCLA could not absorb another serious injury.

Already down their best defender, the Bruins lost another starter early in the second half Friday night at T-Mobile Arena when Bona stayed down for a lengthy stretch before getting up and walking slowly to the locker room.

The absence of Bona alongside Jaylen Clark, who was out because of a lower-leg injury, briefly left UCLA with a lineup that no one could have envisioned in the second half of its Pac-12 tournament semifinal against Oregon.

Starting point guard Tyger Campbell found himself on the court with reserves Abramo Canka, Dylan Andrews, Will McClendon and Kenneth Nwuba. No matter. For a few breathless minutes, Campbell was all his team needed.

Campbell took over with an array of moves, causing the decibel level inside the arena to rise with each one.

There was a long jumper he banked in from the top of the key.

A crossover dribble followed by a jumper.

A three-pointer.

Another jumper that forced the Ducks to call a timeout as Oregon coach Dana Altman scrunched his face in disgust.

For maybe the first time all season, Campbell was in the full “Steph mode” that coach Mick Cronin had long prescribed. Campbell’s hot streak carried the second-ranked and top-seeded Bruins to a 75-56 runaway victory over the fourth-seeded Ducks.

“It was like poetry,” UCLA guard David Singleton said of Campbell, who scored 11 points in less than five minutes before finishing with 20 of his career-high 28 points in the second half. “It was amazing.”

Bona returned to the bench to cheer on his team to its 12th consecutive victory, smiling and celebrating as the Bruins closed the game with a 29-13 run. He had four points, four rebounds and two blocks in 18 minutes.

Bona’s status for the championship game against Arizona on Saturday was not immediately known. Arizona defeated Arizona State 78-59 in the other semifinal.

“I have no idea,” Cronin said. “He looks good in the locker room.”

Forward Jaime Jaquez Jr. had 18 points and 10 rebounds and Singleton scored 12 points for the Bruins (29-4), who transformed a three-point lead into a double-digit cushion thanks to Campbell’s barrage of points that largely came off midrange jumpers in pick-and-roll situations.

“I was really just trying to make anything happen,” said Campbell, who had been asked before the season to become more of a high-volume shooter a la the Golden State Warriors’ Stephen Curry. “I believe in myself as a player and any shot I take I feel like it’s going to go in, and they just went in today.”

Guard Will Richardson scored 10 points for the Ducks (19-14), who might have lost their last chance at securing an NCAA tournament bid.

Oregon couldn’t sustain the 22-13 rebounding edge it built in the first half, outrebounding the Bruins by only one after halftime even with Bona sitting out the final 16 minutes.

“They’re bigger than us at every position,” Cronin said. “But it’s not how big you are. It’s how tough you are.”

Symbolizing the way his team came together, Nwuba made two huge blocks to spark the late surge after Bona departed. The backup center surprised even himself given that he had spent the last month dealing with soreness in his hip. He said he’s now about 95% recovered.

“Getting those two blocks today made me feel very awoke,” Nwuba said, “like, oh, yes, I’m back, I can go get it.”

UCLA’s Adem Bona gestures for help from trainers after he was hurt diving for a loose ball against Oregon. His status for the title game Saturday was not immediately known.

(Ethan Miller / Getty Images)

UCLA was literally cursing itself at halftime, backup center Mac Etienne uttering profanity on his way off the court after missing a gimme at the rim in the final second of the first half off a great pass from Campbell in transition.

The Bruins’ 32-30 lead at that point came courtesy of tight defense and a nice burst off the bench from Andrews.

The freshman guard followed a floater with a jumper before throwing a perfect lob to Bona for a monstrous dunk.

It was just another step-up performance from a player who had resided mostly in the shadows.

“They practice hard, we prepare ‘em for a reason, we try to tell ‘em their moment’s going to come,” Cronin said.

“We tell ‘em all year, ‘Your moment’s going to come in March and we’re going to need you.’ ”

Depending on Bona’s shoulder, they might need even more Saturday.