LOS ANGELES (AP) — Clancy Pendergast is returning to Southern California as the Trojans' defensive coordinator.

USC announced the addition to coach Clay Helton's staff on Monday.

Pendergast returns to the job he held in 2013 under coaches Lane Kiffin, Ed Orgeron and Helton. USC's defense was solid in its lone season under Pendergast, yielding 21.2 points per game and leading the Pac-12 in total defense.

But new coach Steve Sarkisian didn't retain Pendergast in 2014, instead hiring longtime co-worker Justin Wilcox. The 48-year-old Pendergast spent 2014 out of coaching before becoming the San Francisco 49ers' linebackers coach last season.

Sarkisian was fired by USC last October, and Helton was promoted to the full-time job in November. Wilcox's defenses struggled for long stretches last season despite a wealth of five-star talent, and he was fired by Helton along with three other assistants between the regular season and the Trojans' loss to Wisconsin in the Holiday Bowl.

Pendergast spent 15 seasons as an NFL assistant coach, including five years as the Arizona Cardinals' defensive coordinator. Pendergast was Jeff Tedford's defensive coordinator at California from 2010-12.

Earlier, Helton promoted receivers coach Tee Martin to be his new offensive coordinator. Veteran special teams coordinator John Baxter also agreed to return to USC, where he held the same job on Kiffin's staff.

Helton still hasn't filled out his new staff. Marques Tuiasosopo, who coached tight ends and quarterbacks last season at USC, is expected to return to UCLA to be Jim Mora's quarterbacks coach.

Pendergast's return to USC will begin with a tough test. The Trojans open next season against Alabama in Arlington, Texas, on Sept. 3.