Steve Sarkisian said his first day of spring practice as Southern California's new coach "felt different."

It certainly looked different, with the Trojans running 120 plays in less than two hours Tuesday as the former USC assistant began installing his up-tempo spread offense.

"We got a great deal of work done," Sarkisian said. "It didn't feel like — to me — a first practice, and that's a credit to our coaches and to our players for their ability to respond. That being said, there is plenty of room for improvement."

Sarkisian's new approach represents a significant stylistic change for USC, a program long known for coach John McKay's Student Body Right plays and for producing NFL quarterbacks. But after four chaotic seasons under former coach Lane Kiffin, the timing seems right for a change.

"Last year, it was more run a play, everyone kind of talk about it, figure it out," quarterback Cody Kessler said. "This was just, 'Go.'"

Kiffin's time at USC was stop-and-go, ultimately ending five games into last season as he was fired hours after a 62-41 loss at Arizona State. Replaced by beloved defensive assistant Ed Orgeron, USC responded by winning six of its final eight games in the regular season, including a memorable upset of eventual Pac-12 champion Stanford.

Orgeron left USC following Sarkisian's hiring on Dec. 3, with offensive coordinator Clay Helton in charge for the Las Vegas Bowl romp over Fresno State.

The task for Sarkisian is to build on those results while navigating the final year of scholarship reductions imposed by the NCAA resulting from the Reggie Bush case. USC enters camp with 56 players on scholarship, though the actual number available in the spring is significantly smaller because of injuries.

Star defensive tackle Leonard Williams will not participate this spring as he recovers from shoulder surgery, and defensive back Josh Shaw is dealing with a stress fracture in his foot, Sarkisian said.

The main focus for Sarkisian is transitioning to a new approach on offense. He put his team through long stretches of frantically paced action during practice, interrupted by three teaching periods.

"We don't have time to critique our players in between plays because of the tempo we are operating at, and that's designed that way," Sarkisian said. "It is a way that grabs players' attention and that they respond to really well."

In Sarkisian's final season at Washington, the Huskies improved their scoring output by nearly two touchdowns per game from 2012, averaging 37.9 points after the coach introduced the use of tempo.

Now Sarkisian inherits an intriguing group of offensive players, including Kessler, running back Javorius Allen and receiver Nelson Agholor.

Kessler had 2,968 yards passing and 20 touchdown passes in his first season as a starter, winning MVP honors in the bowl game after throwing for a career-high 345 yards and four touchdowns against the Bulldogs. Allen rushed for 14 touchdowns in the nine games after Kiffin was fired, while Agholor led the team with 918 yards receiving.

While Sarkisian said every position is up for grabs, Kessler got all the work with the first team as spring practice started. Rising redshirt freshman Max Browne and early enrollee Jalen Greene are also in the mix and should receive plenty of reps; Max Wittek's transfer left USC without a backup who has seen game action.

"I feel very comfortable, especially after the year that we had," said Kessler, who will be a redshirt junior in the fall. "At the end of the day, I'm not just competing against them (Browne and Greene). In my mind, I'm competing against guys across the country, Brett Hundley and Jameis Winston and guys like that that are elite quarterbacks."

Sarkisian offered no immediate judgments regarding the play of Kessler and the other quarterbacks, citing the demanding pace of practice.

"We're moving at a pretty fast clip out there and you're trying to assess everything at once," Sarkisian said. "It's hard to do that."