TUCSON - Southern California coach Pete Carroll is a defensive coordinator at heart. So Carroll said he wasn’t the least bit concerned when his third-ranked Trojans took a 3-0 lead into the locker room at halftime Saturday night against Arizona.
Nor was he surprised when USC pulled away in the second half for a 20-3 victory, extending their Pac-10 record winning streak to 24 games and setting a record with their 12th straight conference road win.
It wasn’t as exhilarating as many of USC’s victories last year, when the Trojans blitzed opponents with a highpowered offense. But it made Carroll every bit as happy.
‘‘I love the fact that we’re playing defense like this three straight weeks,’’ Carroll said. ‘‘We’re playing like crazy.’’
The Trojans (3-0) limited Arizona to 154 yards, including minus-16 yards on 19 rushes. Arizona converted only two of 12 third downs.
‘‘That’s awesome consistency and discipline about those guys,’’ Carroll said. ‘‘That’s a great job by the defense.’’
The Trojans have allowed 27 points in their first three games. Asked if the defense was carrying the Trojans, quarterback John David Booty said, ‘‘Defense wins championships. If that’s the case, I want to have a good ’D’ here. If they want to carry us, that’s fine with me.’’
The Wildcats have mustered one touchdown in three games against Division I-A teams.
‘‘We’re having a hard time getting into the flow on offense,’’ Arizona coach Mike Stoops said. ‘‘We have to look at some things and try to get better.’’
USC dominated its first two opponents, whipping Arkansas 50-14 on the road and defeating then-No. 19 Nebraska 28-10 in Los Angeles. But the Trojans found themselves in a 60-minute fight against the Wildcats (2-2), who lost to Louisiana State 45-3 two weeks ago.
Leading 3-0 at intermission, the Trojans made it 10-0 when Booty hit Dwayne Jarrett for a 3-yard touchdown pass early in the third quarter. It was Jarrett’s 32nd career touchdown catch, tying the record set by Stanford’s Ken Margerum from 1977-80.
Carroll said afterward that Jarrett, who finished with four catches for 36 yards, had injured his shoulder but provided no details.
USC freshman tailback Emmanuel Moody ran for a game-high 130 yards and one touchdown as the Trojans returned to their powerrunning roots.
‘‘We played SC ball tonight,’’ said Moody, who has emerged from a crowded field of candidates to replace Reggie Bush.
The Trojans gained 381 yards. But they would have been in dire trouble without their defense.
USC made its first stand early in the second quarter, after Arizona created the game’s first scoring chance. Wildcat cornerback Antoine Cason intercepted a Booty pass and returned it 17 yards to the Trojans 32. Cason grew up 30 minutes from the USC campus in Long Beach, Calif., but was not recruited by the Trojans, and he vowed last week to prove they made a mistake.
It was Booty’s first interception in 79 passes since he succeeded Matt Leinart, who visited with his teammates on the field before the game.