LOS ANGELES (AP) Kenan Christon only got in the game because the first three tailbacks on Southern California's depth chart were all hurt and the fourth-stringer had just fumbled.

With the eye-popping speed that made him California's 100-meter high school champion last May, the freshman scored two blazing touchdowns to clinch a blowout win over Arizona.

Although the Trojans are barely outrunning their injury woes, they've still got talent that can burn. They're also still leading the Pac-12 South after a 41-14 victory over the Wildcats on Saturday night.

Christon rushed for 88 of his 103 yards in the fourth quarter of an electrifying debut for the Trojans (4-3, 3-1 Pac-12). The San Diego native flew past the Arizona secondary on a 55-yard TD run early in the fourth quarter, and he added a 30-yard TD sprint down the middle less than five minutes later.

''There's a lot of great football players on this team, so it's hard to judge his speed,'' USC coach Clay Helton said. ''But it's nice to have that feeling and know that when the play breaks, if he's even, he's leavin'.''

Kedon Slovis threw touchdown passes to Michael Pittman Jr. and Tyler Vaughns as USC remained unbeaten at the Coliseum this season and atop the division alongside Utah, which lost to USC last month.

Although Christon provided the fireworks, USC beat Arizona for the seventh straight time mostly because of a dominant defensive performance against Khalil Tate and the Wildcats (4-3, 2-2), holding them to 167 yards and no points in the first three quarters.

''I believe our defense is all together, so when one makes a play, everybody makes a play,'' said USC linebacker Kana'i Mauga, who had 13 tackles and an interception in a breakthrough performance. ''Everybody was hype on the sideline. It was a great atmosphere.''

Tate passed for 47 yards and was sacked six times before touted freshman Grant Gunnell replaced him in the third quarter for the Wildcats, who have lost two straight after a four-game winning streak. USC led 34-0 before Brian Casteel took a short pass from Gunnell 56 yards for Arizona's first points with 12:12 to play.

Gunnell passed for 196 yards and hit Casteel for two touchdowns long after the game was decided.

''We couldn't protect tonight,'' Arizona coach Kevin Sumlin said. ''They got pressure on us even without blitzing. We've got to be able to run the ball more effectively. We weren't consistent enough.''


Slovis passed for 232 yards without a turnover as USC won easily despite six more significant injuries for a team that has already used three quarterbacks this season.

The Trojans began the night without their top three cornerbacks and defensive end Christian Rector due to injury, and they lost top safety Talanoa Hufanga to a shoulder injury in the first half and star freshman defensive end Drake Jackson to an ankle injury in the second half. Running backs Stephen Carr (hamstring) and Markese Stepp (ankle) also picked up injuries during the game.

Enter Christon, who looked ready for the spotlight while taking handoffs from Slovis, whose freshman breakthrough performance due to an injury occurred just six weeks ago.

''I just followed my blockers and the O-line opened up a huge hole for me,'' Christon said of his first TD run.


USC's defense caused constant problems for Tate from the opening drive, and the Trojans scored their first 10 points on short fields created by Arizona turnovers. Stepp then capped an 87-yard drive by scoring from 12 yards out to put USC up 17-0 shortly before halftime.

Gunnell threw an interception shortly after relieving Tate, leading to three more points for USC.

''We just didn't connect as a unit,'' said Arizona running back J.J. Taylor, who rushed for 80 yards. ''We've got to put everything together to be successful. We've just got to game-plan better for next time.''


Tate missed his final chance to beat USC during his career with the Wildcats out of nearby Serra High, a hotbed for Trojans talent. The Inglewood native made his first career start against USC as a 17-year-old freshman, but failed in four opportunities for a win over his hometown program.


Arizona: Sumlin said immediately after the game that Tate will start next week, but the Wildcats have a decision to make at the position soon. Tate's struggles in Los Angeles obviously weren't entirely his fault, but Gunnell is the future for a program that might need to move on from Tate's thrilling, but not incredibly successful, tenure.

USC: The Trojans have plenty of work to do, but they're still in the driver's seat in the Pac-12 South with their win over Utah. Injuries could be the biggest obstacle between USC and the league title game, but the Trojans looked fairly sharp while moving one step closer.


Arizona: Another trip to California to face struggling Stanford on Saturday.

USC: A short week of preparation for a trip to snowy Colorado on Friday night.


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