Cowan gets most of practice work

An abbreviated quarterback competition at UCLA was altered Tuesday, after Ben Olson “tweaked” his already sore left knee doing individual workouts.

Olson, Patrick Cowan and Osaar Rasshan were to have the same amount of reps with the offense during practice, Coach Karl Dorrell said. That plan changed when Olson pulled up lame.

Cowan, who has missed the last two games after suffering a collapsed lung, did the majority of the work, as the Bruins prepared to face No. 8 USC on Saturday at the Coliseum. Rasshan and Olson both played a half in a 16-0 victory over Oregon on Saturday.

“Ben was sore today, and I knew that was going to be the case given what he did this past weekend,” Dorrell said. “So we decided not to give him any reps today. He doesn’t have any swelling, it’s just sore.”

Olson spent the entire practice watching as Cowan did most of the work at quarterback.

“I kind of tweaked it a little bit during individual drills,” Olson said. “It happened last year too, when I was coming back from that [knee] injury.

“I’ll be fine tomorrow and be raring to go. I had a good idea that since it was sore yesterday, it would be sore today.”

Still, the news wasn’t good for the Bruins, who are sifting through their quarterback situation trying to come up with a starter against the Trojans.

Olson missed four games with the knee injury before playing the second half against Oregon.

Rasshan had moved to wide receiver last summer, but was back at quarterback after Olson was injured against Notre Dame. Rasshan suffered a minor sprained ankle against Oregon, Dorrell said.

Cowan suffered a concussion and collapsed lung against Arizona on Nov. 3. But as of Tuesday, Cowan was getting the most work.

“To be truthful, they didn’t let me know what reps I would be getting,” Cowan said. “I did all the work with the first team. That’s what they needed me to do today, so that’s what I did.

“I was a little winded, but it was a lot of fun being out there with the team.”

Said Dorrell: “We’re going to announce something soon what we’re doing there [at quarterback].”

He has said the Bruins may use all three during the game Saturday.

Cowan, who was allowed to talk to the media for the first time since being injured, said he wasn’t overly concerned after suffering the collapsed lung.

“I don’t think it was the actual injury that got to me, it was just getting injured again,” Cowan said. “It was just something else.”

Cowan suffered a hamstring injury before the season and missed the first three games. He started against Washington on Sept. 22, but injured his right knee in that game.

He was cleared to begin conditioning last week after tests determined the lung had healed.

“It wasn’t just football-wise, I was happy enough to be healthy again,” Cowan said.

Rasshan said he was “shocked” to be pulled out of the Oregon game after halftime with UCLA leading, 6-0. It was his second start, coming two weeks after playing in a 24-20 loss to Arizona State.

“I felt we have been a second-half team for the most part,” said Rasshan, who didn’t complete a pass in seven attempts against the Ducks. “The offense has struggled a lot this year. . . . [Against] Arizona State, we started slow, then we put up a lot of numbers in the second half. So I was shocked to be pulled out [of the Oregon game].

“They told me I was possibly going to get back in. I guess they were trying to get a little boost with Ben. He seemed to do well.”

The Bruins did not practice in full pads Tuesday. . . . Tailback Craig Sheppard, who has the last two touchdowns the Bruins’ offense has scored, sat out practice with a groin injury. . . . Linebacker John Hale practiced for the first time since suffering a hamstring injury against California on Oct. 20. . . . Strong safety Chris Horton (concussion) was allowed to do individual drills Tuesday and is expected to return to full practice today.

chris.foster@latimes.com