Sanchez entered spring practice after the 2008 season as the front-runner to take over the starting quarterback position, but faced strong competition from redshirt freshman Aaron Corp and Mitch Mustain, a transfer from Arkansas, where he had been the starting quarterback; Mustain, like Sanchez, was named the top quarterback in the nation upon the conclusion of high school career in 2006. By the end of spring practice, Carroll announced Sanchez would be the starting quarterback heading into the fall. During the first week of fall camp, Sanchez dislocated his left kneecap during warm-ups prior to practice; trainers immediately put the kneecap back into place. After missing nearly three weeks, Sanchez was cleared to play in the opener against Virginia. Before the opener, Sanchez was contacted by USC's previous three quarterbacks—Carson Palmer, Leinart and Booty—who wished him well and offered general advice.