LOS ANGELES -- Cameron Smith returned the second of his three interceptions 54 yards for a touchdown, and Southern California knocked No. 3 Utah from the unbeaten ranks with a 42-24 victory Saturday night.
Ronald Jones II, Justin Davis and fullback Soma Vainuku rushed for scores to help the Trojans (4-3, 2-2 Pac-12) snap their two-game skid and earn a victory for interim coach Clay Helton in his debut game at the Coliseum.
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Cody Kessler passed for 264 yards and a touchdown and rushed for another score, while JuJu Smith-Schuster had eight catches for 143 yards and a fourth-quarter TD that wrapped up the win.
Britain Covey caught two touchdown passes for the Utes (6-1, 3-1), whose eight-game winning streak ended.
Smith, USC's dynamic freshman linebacker, led a fine defensive performance by picking off Travis Wilson's throws and making three returns for a combined 122 yards, including his scoring romp down the USC sideline 1:07 before halftime.
Utah was second in the nation in turnover margin entering the game, forcing 19 turnovers and committing just seven. The Trojans erased that advantage thanks to Smith, the first USC player with three interceptions in a game since Jason Oliver in 1991 against Penn State.
While Wilson threw four interceptions during a rough night for the Orange County native, Utah also inexplicably failed to establish its running game against USC, which had been bullied up front this season. Star tailback Devontae Booker had just 14 carries for 62 yards, and Bubba Poole rushed for a score.
USC, which lost its previous two home games to Stanford and Washington, kept Utah winless in Los Angeles since 1916.
The Trojans were outstanding in their first appearance at the Coliseum since an embarrassing loss to Washington and the subsequent firing of coach Steve Sarkisian nearly two weeks ago. After Helton took over for last week's narrow loss at Notre Dame, he became the eighth straight USC coach to win his first home game.
The tumult-plagued Trojans entered the night as slight betting favorites against the powerful Utes, and USC proved Vegas' prescience with an excellent game plan that largely played to its strengths. Jones and Davis combined for 139 yards rushing, and Smith led an aggressive defensive effort that limited Utah to 213 yards in the first three quarters.
USC went 88 yards for Davis' TD run on its opening drive, but Utah answered with a 30-yard TD catch by Covey, the 5-foot-8 freshman.
The Trojans evened it after Smith's 41-yard interception return led to Vainuku's fourth-down TD dive, and they took the lead on a vicious 18-yard TD run up the middle by Jones. Moments later, Smith took his second interception to the house, putting the Trojans up 28-14.
Kessler's 1-yard TD dive on fourth down accounted for the only points of the third quarter, and he hit Schuster for a beautiful over-the-shoulder TD catch in the fourth.
USC played without injured receivers Steven Mitchell Jr. and Darreus Rogers and three key offensive linemen: center Max Tuerk, left tackle Chad Wheeler and backup center Toa Lobendahn, who was injured in the first half. Utah was without top linebacker Jared Norris.