With visions of blowouts past ringing in their heads, the Arizona defense held No. 3 USC to a 3-0 halftime lead Saturday at Arizona Stadium, the fewest points the Trojans had scored by the midway mark since last October against ASU.

But more importantly, it meant all the Wildcat offense had to do was find the end zone once – just once – and the game’s momentum could have been enough from there to carry the team to a breakthrough upset.

Thirty minutes and no red-zone trips later, however, the Wildcats were stuck on the wrong side of a 20-3 outcome, one they seemed too inept to affect from the get-go.

“”Our execution needs to get better offensively. We missed too many things,”” said UA head coach Mike Stoops. “”We’re playing a lot of young guys, and some of it’s our lack of experience and our lack of big-play style of guys, and that’s something we need to develop in this program. That’s obviously all of our responsibility.””

The Wildcats won’t need to look long at Saturday’s film to assess who deserves the biggest share of the blame.

Although Arizona’s defense held USC to its lowest point total in four years, the Wildcat run game was similarly jaw-dropping, finishing with the team’s fewest net yards – minus-16 – since 2002.

Running back Chris Jennings turned in a subpar second start, finishing with nine carries for 23 yards a week after turning in a 201-yard performance that ranked 10th in school history.

Yet it was the five sacks on sophomore quarterback Willie Tuitama, totaling a loss of 39 yards, that not only doomed the team on the stat sheet but also reflected the blatant mismatch Saturday between the Arizona offensive line and the Trojans’ vaunted front seven.

Facing constant blitzing, Tuitama overthrew receivers on many passes and missed just high on others, but he seemed to finally find a rhythm with 10 minutes remaining. At that juncture, he completed four straight passes to wide receiver Mike Thomas, only to take his last sack and move the team, down 13-3, out of scoring position.

Tuitama finished without a passing touchdown for the second time in three games, after throwing one in the fourth quarter against Stephen F. Austin, and threw an interception in his third straight start.

He said he was caught off-guard by the variety of USC’s pass-rush techniques – particularly a linebacker-cornerback blitz from his weak side that led to his third sack in the second quarter.

Tuitama suggested the team could start mixing up its play-calling to keep defenses honest.

“”When we throw the ball, we move the ball,”” he said, alluding to long catches by Thomas and fellow receiver Syndric Steptoe. “”Maybe instead of trying to let the run game open up the pass, our pass game could open up the run.

“”(But) I trust the coaches and their schemes. We just got to come out there and do what we can do.””

The offense’s underwhelming performance put a damper on Arizona’s sterling effort on the other side of the ball.

Although the Wildcats allowed 381 yards of total offense and 22 first downs, the figures were roughly half of what the team conceded against the Trojans in 2005, when running back LenDale White finished with four rushing touchdowns himself.

In fact, true freshman running back Emmanuel Moody (130 yards, two touchdowns) was the only USC player to put on a reasonable facsimile of last season, as the Wildcats finally put a clamp down on the passing game.

Cornerback Antoine Cason appeared to win his battle with All-America receiver Dwayne Jarrett, who entered Saturday averaging 130 yards receiving and two touchdowns in his career against Arizona.

Cason finished with a team-high-tying 12 tackles and stepped in front of Jarrett to intercept John David Booty in the second quarter.

“”I had to show them that you come attack me, you get what you come for,”” said Cason, who limited the junior wideout to four catches for 36 yards and a score. “”I just played hard for my teammates, with intensity. I played as hard as I could.””

The defense held USC, who had scored at least 40 points in the teams’ last four meetings, to 13 points until just over three minutes remained in the game, when Thomas miffed a fair catch on a punt return and gave the Trojans the ball on the Arizona 9-yard-line.

Moody made up the difference with a touchdown run on the next snap, all but sealing USC’s victory thanks to another mistake by a key offensive player.

“”We have to have some guys step up on all areas of the ball and do some good things,”” said linebacker Spencer Larsen, who also had 12 tackles. “”We just need to make better plays and big plays.

“”We need them.””