LOS ANGELES (AP) Oregon State's defense and special teams did its part to break a 23-game losing streak at the Coliseum that dates to the Eisenhower administration.
The Beavers' offensive failures, however, ensured that at least one more President will be added to the roster of Commanders in Chief during a run of futility that goes back to 1960.
The Beavers (3-1, 0-1 Pac-12) managed a woeful 181 yards and didn't score an offensive touchdown for the first time since a November 2011 loss to California.
''The story of the game was we never responded offensively, to score points or to control the ball, and our defense wore out,'' Riley said. ''I would say we were probably disruptive. That was probably the best way to put our offensive performance.''
Darreus Rogers caught a 48-yard Hail Mary touchdown pass at the halftime gun as the Trojans (3-1, 2-0 Pac-12) rebounded smartly from their first loss with solid defense and another stellar game from Kessler, who went 24 for 32 while leading a 461-yard offensive performance.
The Trojans had a bye after their upset loss at Boston College knocked them out of the Top 10. USC started tentatively in its first game back at the Coliseum, but Su'a Cravens' clever interception lit a spark.
''I think it was just sloppy on my part,'' Mannion said. ''I take full responsibility for our offensive performance. I expect a lot more out of myself, and I'm certainly not satisfied with the way I played and the way our offense played as a whole.''
Davis caught a 16-yard TD pass and ran for a fourth-quarter score for the Trojans. Javorius Allen added 115 yards rushing and a touchdown as USC roared back from an early deficit, scoring the final 28 points and playing 41 shutout minutes.
''We just had to get back to the basics to get over a loss,'' said Cravens, who also had a team-leading six tackles and a sack. ''We had to do our job and execute.''
Despite 14 penalties for 124 yards, the Trojans moved the ball steadily when their defense wasn't thoroughly stifling Oregon State, which managed only 63 yards and no points after taking a 10-7 lead early in the second quarter.
Ryan Murphy returned a kickoff 97 yards for a TD for Oregon State, which struggled in its first serious test of the season. Mannion went 15 of 32 for 123 yards with two interceptions for the Beavers.
''Even though we weren't doing much offensively, our defense played a lot of good football there for a long time,'' Riley said. ''I think our team had some confidence we could do some stuff.''
Oregon State showed little of its usual offensive pop after three straight victories over lower-tier opponents to open the season, and Mannion didn't look sharp in the California native's first appearance at the Coliseum.
After Cravens' first career touchdown in the first quarter, Murphy took the ensuing kickoff straight down the Beavers' sideline for a TD, making the fifth-longest kick return in school history on his first career return. Murphy has been lobbying Riley for a spot on kick returns.
''I guess he proved his point,'' Riley said. ''He's a good football player. He made a lot of good plays in this game and really played his heart out, too.''
But Oregon State was unable to match its early success running the ball - although Storm Woods finished with 61 yards rushing on nine carries and added 17 yards receiving on three catches - with any of the big plays in the passing game that have propelled Mannion to third on the Pac-12's career passing yards list.
''Our defense answered. Our special teams answered. That's a mistake that I've got to clean up and I take responsibility for,'' Mannion said.
As the first half ended, Kessler ducked away from several tacklers and launched a pass to the goal line. Several Beavers defenders did little to stop Rogers, whose biggest competition for the ball was from a teammate.
Oregon State lost starting defensive tackle Jalen Grimble, the brother of former USC tight end Xavier Grimble, to a knee injury. Riley did not immediately know the extent of the injury.