Mark Sanchez races 80 yards, picks out one of his buddies and leapfrogs the kneeling player.

Sanchez doesn't need caffeine to summon immense stores of energy. Now, it's a matter of funneling all that zeal in the right direction. That's not easy when you're making your first start in front of 90,000 restless fans.

After a stunning loss to Stanford, USC is preparing to play Arizona with the former Mission Viejo High star as its starting quarterback. Coach Pete Carroll said John David Booty might not start even if his broken right middle finger is causing him little pain by kickoff.

"John might be able to play Saturday but then what happens the next week and the next week," Carroll said. "How long do we prolong this good, solid return? If we give him a break, maybe he can come back strong and be ready to finish the season."

After watching two sloppy offensive performances, USC coaches don't need Sanchez's attention to be running a million different directions Saturday. They need him to be a calming influence on an offense that has turned the ball over eight times in the past two weeks.

"It's a tough atmosphere not to get excited about. Everything inside me wants to just jump out of my skin and be jacked up," Sanchez said. "I think I need to just be cool and show the guys that I can play this game and I'm ready to lead this team."

But who could blame Sanchez for being excited? When he committed to USC three years ago, few people expected him to wait this long to leave his mark. Sanchez wasn't just another high school star in a long line of touted recruits. He was Parade's 2004 Player of the Year.

Since then, he has largely disappeared from the public's gaze. Even now, Sanchez is far from guaranteed to be the quarterback of USC's future. Arkansas transfer Mitch Mustain will be eligible to give him competition next spring.

Considering his high profile, most of the nation's college football coaches would have taken his calls if he had ever considered leaving. Instead, he bided his team, much as Booty did.

"It's real tough. Most kids don't do it these days. Most kids leave," Sanchez's high-school coach, Bob Johnson said. "It's a tribute to Mark in this play-me-or-trade-me mentality kids have now that he didn't transfer.

"If good things happen to good people, then Mark is due a lot of good things."

The only things most college football fans know about Sanchez is that he was a big-time recruit and that he got in trouble with the law. Sanchez was arrested for suspicion of sexual assault in the spring of 2006, but the charges were dropped two months later.

Anonymity can sometimes benefit a quarterback in the public eye. After the Stanford game, fan message boards lit up with people clamoring for Sanchez over Booty, who threw four interceptions.

Oddly, Sanchez always has been the quarterback who is more willing to take deep shots and more willing to risk interceptions. He has thrown two interceptions in just 10 career passes.

Booty can draw the Brett Favre comparisons for his Louisiana drawl, but Sanchez plays more like him.

He is more mobile than Booty and more likely to attempt high-risk plays.

"Our personalities, I don't think really matter right now," Sanchez said. "It's a matter of playing Arizona, playing for this game, managing the game, not trying to be anybody else, just being me and taking the keys to this awesome sports car that we have here and not crashing."

The Trojans will be playing with a baby-faced group of skill players Saturday. Fullback Stanley Havili, tailback Joe McKnight, receivers David Ausberry and Ronald Johnson are freshmen. Vidal Hazelton is a sophomore. With Sanchez at quarterback, the coaches likely will scale back the complexity of the offense.

The receivers say they don't mind that Sanchez will play Saturday.

"Mark just throws a little bit harder. He's a little more aggressive," Ausberry said. "He wants to get things going. I'm ready for it. We're not going to lose a bit. I honestly don't think so."

Sanchez's father, Nick, is a captain with the Orange County Fire Authority. He grew up in the neighborhood around USC and attends most of the Trojans practices. Nick Sanchez prepared Mark from his high-school years to handle the high profile that comes with his position.

He would interview him after his high-school games.

"I'd say, `Oh, it was good,' and he'd be like, `What does that mean? Tell me what you feel. Say you're going to say it to so-and-so from the Register or so-and-so from the Times,' "Sanchez said.