LOS ANGELES — After 30 breathtaking minutes filled with electrifying plays and flying flags, Oregon fans had to hold their collective breath for a few chilling minutes in the third quarter.

As Justin Herbert delivered a pass to Darrian Felix for a 19-yard gain on the first drive of the second half, USC safety Chase Williams made a dangerous hit on the potential NFL franchise quarterback’s left knee.

Williams was assessed a 15-yard penalty for roughing the passer. Herbert, after crumpling on the grass in agony, finally limped off the field. Backup Tyler Shough completed a pass to keep the chains moving.

And then Herbert made a statement about his health, and perhaps to the rest of chairman Rob Mullens’ College Football Playoff selection committee about his team, by throwing touchdown passes of 15, 11 and 37 yards to Juwan Johnson to stick the Trojan Sword into embattled coach Clay Helton.

No. 7 Oregon extended its winning streak to eight games and cleared the tallest remaining hurdle on the way to the Pac-12 championship game with a 56-24 victory over USC on Saturday night in front of a crowd of 63,011 at the Los Angeles Memorial Coliseum.

The Ducks (8-1, 6-0) turned four turnovers by the Trojans (5-4, 4-2) into 28 points.

On Fox’s “Big Noon Kickoff Show,” former USC quarterback Matt Leinart, who was honored during the game as the newest member of the Rose Bowl Hall of Fame, said the Trojans needed to “force Justin Herbert to beat you.”

Herbert, whose streak of 35 consecutive games with a touchdown pass was snapped during last week’s 37-35 win over Washington State, finished 21-for-26 (81%) passing for 225 yards yards with four total touchdowns (one rushing) and one interception.

Oregon knocked USC out of first place in the South Division to the delight of No. 9 Utah, which won 33-28 at Washington in the other key conference matchup.

True freshman quarterback Kedon Slovis completed 32 of his USC-record 57 pass attempts for 264 yards with three touchdowns and three interceptions.

During mop-up duty, Shough capped Oregon’s 56-7 run with a 35-yard touchdown to Mycah Pittman, the younger brother of USC star Michael Pittman Jr.

Brady Breeze recovered a fumble in the red zone and baited Slovis into an interception that the senior safety returned for a touchdown during a wild first half.

MyKael Wright returned a kickoff 100 yards for a touchdown with eight seconds left to give the Ducks a 28-17 lead at the break.

The freshman’s 36-yard kickoff return set Oregon up with manageable field position for the game-winning drive against Washington State.

The Ducks dug themselves a double-digit deficit and were making uncharacteristic mistakes, including left tackle Penei Sewell allowing only the second sack of his career, in the first quarter.

Then freshman safety Verone McKinley flipped the momentum with his fourth interception, which led to a 10-yard touchdown run by Herbert to get the Ducks within 10-7 with 10:11 remaining in the second quarter.

After defensive tackle Austin Faoliu was ejected from the game for drawing two unsportsmanlike penalties on one play, which set up a first-and-goal for USC, Andy Avalos’ unit came up with another timely turnover.

Outside linebacker La’Mar Winston strip-sacked Slovis and Breeze recovered the fumble at the 7-yard line.

Then the Trojans lost their composure with a personal foul on cornerback Olaiijah Griffin and a roughing the passer call on defensive tackle Jay Tuffele.

The Ducks took advantage of the miscues by finishing the drive with a 2-yard touchdown run by Jaylon Redd for a 14-10 lead.

Moments later, Breeze’s pick-six made it 21 unanswered points by Oregon.

Cooler heads did not prevail, however, as a roughing the passer call on Troy Dye and a personal foul on Isaac Slade-Matautia helped to set up Slovis’ 6-yard touchdown pass to Michael Pittman Jr. with 20 seconds left in the half.

Wright house call on the ensuing kickoff made the score 28-17 with eight seconds remaining in the first half.

With Camden Lewis sending the next kickoff out of bounds for a 15-yard flag, Oregon finished the first half with nine accepted penalties totaling 112 yards.

The Trojans won the coin toss, elected to receive the ball and opened the game with a 16-play, 77-yard drive capped with an 8-yard touchdown pass from Slovis to Drake London.

USC was 4-for-4 on third-down conversions, including a pass-interference call against cornerback Deommodore Lenoir, en route to a 7-0 lead.

Lenoir atoned for his sin by intercepting Slovis and returning the ball 45 yards to set up Herbert’s second touchdown strike to Johnson in the third quarter.

Herbert had Jaylon Redd open for a potential touchdown pass on third-and-17 but the slightly under thrown pass was broken up by Greg Johnson.

Lenoir was called for a questionable pass-interference penalty on USC’s second drive, but Troy Dye — playing with a club cast on his broken thumb — made a timely tackle for loss on a third-and-1 to force a punt.

Herbert’s second interception of the season, made by safety Isaiah Pole-Mao on third-and-6, was returned 14 yards to the Oregon 8-yard line.

Lenoir made broke up a pass on third-and-goal from the 6 to limit the damage from the turnover to a 24-yard field goal by Chase McGrath, which gave the Trojans a 10-0 lead with 3:00 remaining in the first quarter.

Follow Ryan Thorburn on Twitter @RGDuckFootball and email podcast mailbag questions to rthorburn@registerguard.com. For more Oregon sports coverage, visit DuckSports.com.