Chased by demons of past sins, pursuing the ghosts of past greatness, the top-ranked USC football team began the 2012 season by swathing the rollicking Coliseum with one chilling word.

Scary.

The Trojans looked so good in a 49-10 defeat of Hawaii, it’s scary. The Trojans also looked so vulnerable in the wake of allegations of more NCAA infractions, it’s scary.

In their first game after two years on probation Saturday, the sprinting and soaring USC players have never looked more free. But with this latest off-field mess settling upon their heads shortly before the game, the Trojans program could again be tied up in knots.

Matt Barkley was dominating, Marqise Lee was untouchable, and 93,607 fans danced through the tunnels on their way to the most jubilantly promising season in several years. But, like the usual early-season humidity, the air was clogged with familiar doubts.

As one should always do in these complicated USC sagas, let’s start with the car. Hours before the Trojans took the field Saturday, The Times reported that former Los Angeles County assessor’s employee Scott Schenter has admitted giving a Chevrolet Monte Carlo to former Trojan running back Joe McKnight during the 2009 season.

The bad news for the Trojans is that this particular infraction was not included in the laundry list of items that landed them on a two-year probation, and it does not fall outside the NCAA’s four-year statute of limitations that would have prevented them from being penalized for it.

The good news for the Trojans is that the NCAA might consider it unseemly to level another stiff sentence on a program for something that happened before it was punished, torn down, and rebuilt under Mr. Clean, er, Pat Haden.

The guess here is that the McKnight case will warrant a stiff slap, but nothing that would keep the loaded Trojans from being allowed to continue their newfound pursuit of a national championship. This would be fortunate for the screaming fans who filled the Coliseum with a November intensity because, yeah, these guys are going for it.

“This was awesome, just awesome,” defensive coordinator Ed Orgeron said, beaming through his sweat. “To see these kids back on the field, to see the Coliseum loaded again, to see us playing football like this again, it was awesome.”

The first play of the 2012 season? The first play of the noble return of quarterback Barkley? The first play for football’s most exciting receiver Lee? All three questions had the same answer, a quick toss from Barkley that Lee juked and looped from downtown to Pomona for a 75-yard touchdown.

“Just one move,” said Lee, humbly shrugging after what seemed like a dozen moves.

The first hit of the 2012 season? The first unleashing of two years of Trojans frustration? Redshirt freshman Soma Vainuku knocked the stuffing out of Hawaii kick returner Will Gregory, causing a fumble that that Warriors recovered.

Two plays, two highlights, and the Trojans rolled from there. Barkley had 220 passing yards — in the first quarter. On new running back Silas Redd’s fourth touch, he ran 31 yards for a touchdown, leaving Penn State a distant speck in the rearview mirror. The Trojans defense welcomed back Hawaii Coach Norm Chow by allowing only 107 yards in the first half, with an interception return for a touchdown by Hayes Pullard, finishing this game before it started.

“We hold ourselves to a high standard, we made the plays all summer so you’d expect these guys to make those plays tonight, and they did,” Barkley said.

This was the first primary in Barkley’s potential election to the Heisman Trophy, and he didn’t disappoint, with 372 yards passing, four touchdowns and no interceptions. But lots of folks watching this game were even more wowed by Lee, who also returned a kickoff 100 yards for a touchdown, giving him 297 total yards.

Barkley might also be hurt, frankly, by the perception that his head coach, Lane Kiffin, is working too hard to win him the trophy. Here’s guessing folks back East will be filled with questions about Barkley’s 11-yard touchdown pass to Randall Telfer early in the fourth quarter on a fourth-and-three play with the Trojans leading by 32 points.

“We’re not playing for ourselves, we’re playing for our school,” said Barkley, bristling when asked about public perception. “If you start to look outwardly, if you start to play for the hype, it doesn’t happen.”

The Trojans could be as good as that hype. But as the McKnight revelations remind them, the minute they start believing they are untouchable is the minute they are most vunerable to collapse.

A bit of the old Trojans arrogance seemed to peek out of this new program’s shell earlier this week when it was revealed that, unlike at other prominent schools, USC is not allowing visiting opponents access to the Coliseum for the customary walk-through on the day before games. Kiffin has said he’s worried about opponents’ tearing up the field, which is just silly. Just ask them to wear tennis shoes, right?

Then, during the blowout game, the Trojans seemed to swagger a bit too much in attempting a two-point conversion after three consecutive touchdowns because they said kicker Andre Heidari was injured. Yet Heidari kicked a 28-yard field goal soon afterward.

A great Trojans start. A scary Trojans start.

bill.plaschke@latimes.com

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