After an 0-2 start, Oregon State coach Mike Riley has made a change at quarterback.
Mannion first replaced Katz in the opener against Sacramento State, a shocking 29-28 home defeat to an FCS team. While Katz started at Wisconsin, Mannion played nearly the entire game.
Katz, a big-armed junior, passed for 2,400 yards and 18 touchdowns with 11 interceptions in 2010 and seemed poised for a breakthrough this fall. But he quickly lost traction with a poor first half against Sacramento State as Mannion came off the bench and led a comeback that fell just short.
The Beavers have a bye this week. They will play host to UCLA on Sept. 24.
Ted Miller covers the Pac-12 for ESPN.com.