Taylor Graham, Jabari Ruffin

USC linebacker Jabari Ruffin tries to bring down Hawaii quarterback Taylor Graham during a game last season at Aloha Stadium. (Wally Skalij / Los Angeles Times / August 29, 2013)

USC linebacker Jabari Ruffin, who appeared on track to possibly start, will be sidelined for the season because of a torn knee ligament, the school announced Sunday night.

Ruffin, a third-year sophomore, was injured after intercepting a pass during a morning workout.

“This is very unfortunate news about Jabari, but I know he will rehab well and come back strong next year,” Coach Steve Sarkisian said in a statement. “And, I know our team will step up in his absence.”

The 6-foot-3, 240-pound Ruffin, who came to USC from Downey High, was enjoying a productive training camp.

He intercepted a pass by Max Browne, but was injured when tackled during the return. Ruffin was helped to the sideline by trainers and spent the rest of practice with an ice pack on his knee.

Senior J.R. Tavai, third-year sophomore Scott Felix and sophomore Quinton Powell are other outside linebackers competing for starting roles.

Ruffin is the second player to suffer a season-ending knee injury. Defensive lineman Kenny Bigelow was injured during a players-only workout in July.

Sarkisian has spoken of managing a roster that is still depleted in the aftermath of NCAA sanctions.

Last week, defensive lineman Antwaun Woods suffered an elbow injury that could sideline him for a few weeks.

Sarkisian said Sunday that defensive lineman Cody Temple suffered a concussion during the Trojans' first full-pads workout Friday.

On Sunday, receiver Darreus Rogers rested a sore Achilles' tendon and multipurpose player Adoree' Jackson sat out much of practice after another player stepped on his foot. Defensive lineman Leonard Williams was held out after taking a hit to his left shoulder. Williams is recovering from right shoulder surgery.

Sarkisian said all players would be evaluated but he did not expect any of Sunday's injuries to be major.

Ruffin's, however, ended his season.

Agholor the elder

Nelson Agholor spent his freshman season as USC's No. 3 receiver behind Robert Woods and Marqise Lee.

Last season, he was the second option until Lee suffered a knee injury in the fifth game against Arizona State.

After averaging 16.4 yards a catch and scoring eight touchdowns as a sophomore, the 21-year-old junior is now the leader of the receiving corps.

“I'm just trying to focus in and make all the plays that come my way,” Agholor said Sunday after a morning practice.

Agholor has made multiple outstanding catches during training camp, teaming with quarterback Cody Kessler on several touchdown pass plays.

“I know where he's going to be every time on the field and, no matter what route it is, I know which way he's going to run it,” Kessler said.