The Lane Kiffin era has officially begun.

There he was, standing in the middle of the field during the first day of spring practice for USC — the young, built coach sporting a white polo, black shorts and white visor pulled low on his forehead, replacing the short, gray-haired, sweatshirt-wearing ball of energy.

Digging in · Sophomore signal-caller Matt Barkley drops back for a pass at Tuesday’s practice. Coach Lane Kiffin said Barkley and senior Mitch Mustain would share snaps at quarterback at the start of spring practice. - Carlo Acenas | Daily Trojan

Immediately, it was evident Pete Carroll was gone.

Within the first few minutes of practice, starting quarterback Matt Barkley and prized recruit, running back Dillon Baxter, ran a lap around the field seemingly for a fumble caused by a poor exchange between the two, something that was rarely seen in the Carroll days.

“We’re going to have to fix our mistakes, just like in a real game,” said Barkley, who couldn’t remember the last time he ran a lap for disciplinary reasons. “I trust [the coaches] and believe they are making us better.”

They weren’t the only players running laps. Wide receiver Brice Butler ran about three laps for showboating after making two separate catches in one-on-one drills.

There were more changes to practice besides the disciplinary measures.

Walking in, it was clear that security was tighter. While DPS officers were present in the past, they were very relaxed and watched practices. Now, a few officers stood facing the crowd with their backs to practice.

On the field, after running a few offensive drills to start, the team spent about 30 minutes focusing on special teams. Kiffin had the offensive and defensive linemen catching punts and running backs and receivers smothering kicks and scooping up loose balls.

“There was a little bit of a different vibe because we were doing new special teams stuff,” running back C.J. Gable said.

When asked if he had ever done that much special teams work before, Gable didn’t think long.

“No, I haven’t,” he said.

Despite these small changes, the practice still had the overall feel of USC practices of old.

The team had an 11-on-11 scrimmage to end practice and the up-tempo style didn’t disappear. If anything, the players were a little too enthused.

“I liked their energy but we have to practice a little smarter,” Kiffin said. “There’s a lot of trying to be Troy Polamalu on day one. We’ve just got to manage the way we practice. But it’s a lot easier to slow them down than speed them up, so that’s good.”

Also familiar were the hundreds of people on the sidelines watching practice. However, most of them were media personnel, former players or family members since the USC staff has decided to limit practice to pre-approved guests who submit requests at least 24 hours in advance.

“I know before it was an open practice, anybody could walk in,” Kiffin said. “We just have changed the way we monitor a little bit, tighten it up and have a process of making sure who’s coming in — obviously for compliance reasons.”

In other on the field news, highly touted freshmen Baxter and wide receiver Kyle Prater took part in all of the team’s drills. Prater is still limited in movement by a sore hamstring but he ran routes with the team and caught passes from Barkley and Mustain. The two quarterbacks split reps throughout practice as Kiffin said they would. Even though Barkley is the incumbent starter, Kiffin declared the quarterback competition open Monday.

Tight ends Rhett Ellison and Blake Ayles didn’t practice. Ellison could miss all of spring practice with mononucleosis; Ayles is suffering from an ankle injury.

Tigpractice. Ellison could be out for all of spring