LOS ANGELES -- UCLA quarterback Kevin Prince attempted to practice Thursday but appeared to aggravate his injured right knee on his first play.
He then walked gingerly to the sideline and did not run another play, further jeopardizing his availability for Saturday's game against Washington State.
Coach Rick Neuheisel said he was going to wait until game time to decide if Prince or backup Richard Brehaut would start Saturday, but it's looking more and more as if the odds are against Prince playing.
"The chances are diminished," Neuheisel said. "But I'm not ruling him out yet."
Players are not available to the media on Thursdays so Prince was unavailable for comment.
Prince injured his right knee last Saturday during UCLA's 34-12 victory over Texas. He had an MRI exam Sunday that revealed no structural damage, but he had fluid drained from the knee and was experiencing pain and swelling.
He sat out of practice Tuesday and Wednesday but came dressed for practice Thursday. He looked fine early in the session during one-on-one passing drills, but on his first snap during a team drill against the scout team, he rolled to the right after handing off to Johnathan Franklin before limping off.
Brehaut, who has been working with the first team all week and took the first series against the scout team, then split reps with Darius Bell for the rest of the practice.
"Richard is preparing like he will go, but I'm not ruling out the chance for Kevin to get back in there," Neuheisel said. "Kevin is working around the clock to get healthy and we can be a good football team when he's healthy. If Richard needs to go, we're going to get fully behind him and get ready to rumble."
Asked why he would risk playing Prince against a Washington State team that has won only one Pac-10 game in two years and is a 27-point underdog against UCLA, Neuheisel said it's because the offense needs continuity.
"We want Kevin to be consistent," Neuheisel said. "We want Kevin to keep growing as a quarterback."
A healthy Prince seems to be vital to the Bruins' chances. He has engineered upset victories in each of the last two weeks, fully participating in practice before each game. But he missed most of fall camp because of a strained oblique leading into the season-opener against Kansas State but started and was rusty as UCLA lost, 31-22.
The next week, a sore shoulder sidelined him and kept him out of practice, but he returned to start against Stanford in a game UCLA lost 35-0.
"I'm not thinking about that," Neuheisel said. "I'm thinking more about the way we have played the last two weeks."
Peter Yoon covers UCLA for ESPNLosAngeles.com. Follow him on Twitter.