CORVALLIS - Oregon State is back to a one-quarterback system.

"We're going to start Sean Mannion at quarterback,'' Beavers coach Mike Riley said after Tuesday's practice.

Mannion had been sharing those duties with incumbent Ryan Katz, but after a loss to Sacramento State of the FCS and a choppy shutout loss to Wisconsin in which the quarterback substitutions did not help, Riley decided to make the announcement now.

"This guy just kept rising and, in our mind, earned the right to be a starter,'' said Riley, who has two weeks to prepare Mannion for the Sept. 24 home game against UCLA.

As for Katz, who started every game last season as well as the first two games of 2011, he becomes simply the backup quarterback.

"I just told him to prepare like a starter,'' Riley said. "It’s a decision he doesn’t like, but it’s out of his hands - that’s a good thing. So he can just grit his teeth and go on and prepare himself to play.''

Katz took all the reps with the second unit Tuesday and, as he has since fall camp began, he looked pretty good. It's just that Mannion - in the coaches' eyes - is a little better.

"It's not him, obviously, getting worse,'' Riley said of Katz. "We thought this other guy was playing better. It's always a relative thing.

"As you rise up in levels, every level has a lot of good players. when they go to the next level, they'll find it even more so.''

Mannion, appearing more at ease without having to discuss the quarterback controversy, said he is thankful for the opportunity.

"I'm going to enjoy it,'' Mannion said. "But at the same time, our focus is on UCLA at this point. It's all we have time to think about, really, is getting better for UCLA.''