Posted by ESPN.com's Ted Miller

It's official: USC quarterback Mark Sanchez will enter the NFL draft, where he's likely to be a first-round draft pick and, perhaps, the first quarterback selected.

So, as I wrote last night, junior Mitch Mustain or sophomore Aaron Corp or touted true freshman Matt Barkley, who already has enrolled in school and will participate in spring practices, will battle to be the next Trojans quarterback.

It's not a bad job. Nine starters return on offense. The only other departure is receiver Patrick Turner.

Mustain, a high-profile transfer from Arkansas, was the 2005 Gatorade, USA Today and Parade Magazine national prep player of the year.

Corp, taller and more mobile than Mustain, was a Parade All-American in 2006.

Mustain has a powerful arm, but also a tendency to believe that arm can force balls into tight spaces. He also started eight games at Arkansas in 2006.

During the regular season, the backup job alternated between them a number of times.

Barkley is the No. 1 player on ESPNU 150, our list of the top 150 prospects in the country.

Barkley winning the job, however, would break the Trojans' pattern of valuing experience under Pete Carroll -- see Matt Leinart beating out John David Booty, Booty beating out Sanchez and Sanchez beating out Corp and Mustain.

Still, this will be one of the marquee competitions heading into the 2009 season, with none of the three candidates owning significant game experience in the Trojans' complicated offense that would distinguish him over the others.