Matt Barkley learned from his mistakes Thursday.
The freshman quarterback with a chance to start USC's Sept. 5 opener against San Jose State had three passes intercepted during a brief morning workout.
Five hours later, the Trojans returned to the field and Barkley did not commit a turnover while taking nearly every first-team snap during a 2 1/2 -hour practice.
"It didn't faze me," Barkley said of the morning miscues.
Turnovers, and the ability to avoid them, will be a determining factor if Aaron Corp returns from a leg injury in time to compete with Barkley to regain his place atop the depth chart.
The strong-armed Barkley was fortunate early in camp when defenders dropped several balls. His luck ran out Thursday when safety Josh Pinkard and defensive back Byron Moore picked off passes in the end zone during a seven-on-seven drill, and linebacker Jarvis Jones intercepted a pass that bounced off receiver Damian Williams' hands during a scrimmage drill.
Barkley, though, regrouped during team meetings.
"He came right back out here and cranked it up," Coach Pete Carroll said.
Actually, Barkley dialed it back.
Carroll and quarterbacks coach Jeremy Bates had said they weren't concerned about Barkley's interceptions because they resulted from advanced plays that the 18-year-old was attempting to execute for the first time.
Barkley, however, clearly took a more cautious approach in the second practice. He completed several difficult throws, a long pass to Travon Patterson among them, but uncharacteristically threw the ball out of bounds on several plays rather than force the issue.
"It's not natural to me," he said of throwing the ball away. "I was kind of mad it wasn't there, and Coach Bates said, 'That's a great play.'
"He's happy with that every time because we get a new down. . . . I'm growing accustomed to it."
Meantime, Corp was outfitted with a knee brace. The sophomore said his leg felt better and that he would perform footwork drills today to test the stability of his fractured left fibula.
Corp, injured Monday, has been undergoing a regimen that includes ice, stretching and massage to get back onto the field.
"Whenever they're open," he said of the training room, "I'm pretty much in there."
Tight end Blake Ayles did not participate in the afternoon workout after undergoing tests for heart arrhythmia.
Ayles, a sophomore, says he has experienced symptoms of an irregular heartbeat since seventh grade.
"It just kind of winds me a little bit," Ayles said. "It scares me a little bit every once in a while, but they said it's nothing life threatening."
Ayles said he would practice today but would continue to be evaluated.
Last month, incoming freshman linebacker Frankie Telfort's USC playing career ended before it began when he was diagnosed with hypertrophic cardiomyopathy, a condition that thickens the heart muscle.
Defensive tackle Averell Spicer could be sidelined for several weeks because of a high ankle sprain suffered Wednesday. Junior Hebron Fangupo continued to work in Spicer's spot. . . . Cornerback Shareece Wright (knee bruise) returned to practice but still needs academic clearance, Carroll said. . . . The Trojans practice today at 4 p.m.