"Our defense did an amazing job," Helton said after a 38-10 rout of Oregon State on Saturday at Los Angeles Memorial Coliseum.
USC quarterback Sam Darnold threw three touchdown passes as the Trojans (5-1, 3-1 Pac-12) overcame a sloppy start that included a muffed punt by Ajene Harris and a fumble on which the ball simply slipped out of Darnold's hand on a pass attempt.
Those two possessions placed Oregon State (1-5, 0-3) inside the USC 30-yard line but yielded zero points, with defensive tackle Kenny Bigelow blocking one field-goal attempt and the other going off course.
A third red-zone opportunity in the first half ended when linebacker Cameron Smith denied Oregon State running back Thomas Tyner on a fourth-down conversion attempt, one play after safety Marvell Tell and defensive end Christian Rector combined for a tackle just shy of the first-down marker.
Tell and Rector finished the afternoon with 10 and seven tackles, respectively, to lead the Trojans. Rector also recovered a fumble deep in Oregon State territory in the second half and returned a short kickoff.
"He's developed so well. We're pumped to see him out there and making plays," Smith said of Rector, who has lined up at three positions in the past four games.
Rector's emergence has been of particular importance for the USC defense, which is without defensive end Porter Gustin. Gustin came out of the Texas game on Sept. 16 due to a biceps injury.
"Having Porter out is awful; we can't wait for him to come back. But it helps Christian is able to play and fill a need," Smith said.
The Beavers were without leading rusher Ryan Nall due to an ankle injury. Replacement starter Artavis Pierce rushed for 60 yards, including a 6-yard touchdown. Quarterback Darell Garretson, starting in place of injured Jake Luton (back), went 16 of 29 for 197 yards, and was intercepted by cornerback Jack Jones.
"I am going to keep battling with them and keep fighting," Oregon State coach Gary Andersen said of his team.
Coming up empty on those red-zone possessions doomed the Beavers, as the misfires came amid a stretch of two Darnold touchdown passes and a 4-yard Ronald Jones II rushing score.
Darnold, who finished 23 of 35 passing for 316 yards, got his first score on a 37-yard bomb to wide receiver Tyler Vaughns. It was Vaughns' first career touchdown reception, one week after Helton said the freshman made a breakthrough.
"Just clicking in the offense, I felt like I was going to have a big game," Vaughns said. "I felt like I was going to have some opportunities."
Darnold also hooked up with Deontay Burnett for Burnett's sixth scoring catch of the season.
Still, USC could not put away the Beavers until the fourth quarter. A Manase Hungalu interception of Darnold in the final minutes of the first half stalled a promising drive and brought the quarterback to nine picks thrown this season -- as many as he threw in the entirety of the 2016 campaign.
USC's first scoring drive after intermission culminated with a 30-yard touchdown pass to Josh Falo -- the third Trojans tight end to catch a pass on the drive. USC was without a tight end reception last week in a loss at Washington State.
The Beavers threatened on the ensuing possession, which included a spectacular diving reception of 33 yards by wide receiver Seth Collins, but a fumbled snap at the USC 6-yard line squandered another red-zone opportunity.
"It was really nothing they did (defensively)," Collins said of the red-zone miscues. "We killed ourselves, really. But we can't have a defeated mindset. We've got six more games."
Collins made another diving grab of 38 yards just before the end of the third quarter. Despite a taunting penalty moving the Beavers back from the 1-yard line, they finally saw the end zone on Pierce's touchdown run.
USC quarterback Matt Fink made his collegiate debut in the fourth quarter. He rushed for a 51-yard touchdown.
"I wanted to show my coach what I could do," Fink said. "I've been dreaming about that type of play since I came here, and I'm excited it came true."
Fink's score was followed by blind long snapper Jake Olson making his second successful point-after attempt snap of the season.
Olson last appeared in the season opener against Western Michigan.
NOTES: Saturday's win was USC's 13th straight at the Coliseum. The Trojans are undefeated at home since Clay Helton became head coach in October 2015. ... USC RB Ronald Jones II has scored at least one touchdown either receiving or rushing in 12 consecutive games dating to the 2016 season. ... USC improved to 9-0 when WR Deontay Burnett catches a touchdown pass. ... Of the five career rushing touchdowns for Oregon State RB Artavis Pierce, three have come in Los Angeles. He reached the end zone twice at UCLA last season.