The Trojans have lost one of their heralded freshmen from the 2017 class in safety Isaiah Pola-Mao, who will undergo season-ending shoulder surgery head coach Clay Helton announced Tuesday evening.

Pola-Mao suffered a shoulder subluxation (partial dislocation) on his right shoulder during Saturday's scrimmage attempting to tackle Ronald Jones, who laid a big hit.

"He had a shoulder that had been going in and out on him, sublexing, so we are going to go ahead and fix that shoulder," Helton said.

Pola-Mao, the nephew of USC legend Troy Polamalu, is the second freshman to undergo season-ending surgery, joining linebacker Tayler Katoa.

The injury isn't a major blow as USC is blessed with safety depth, but Pola-Mao was a contender to contribute on special teams.

- Starting right guard Viane Talamaivao was carted off the field and got x-rays on his foot, which came back negative. Helton expects him back in a couple days.

- Freshman OLB Hunter Echols underwent a successful hip surgery to drain fluid and fix a hip joint infection. Echols attended practice in a scooter. Helton said the former four-star recruit will be out weeks.

- USC had a handful of players return to the mix after missing several practices: WR Keyshawn Young (hamstring), OT Andrew Vorhees (back), TE Josh Falo (bone bruise), WR Velus Jones Jr. (foot) and OC Cole Smith (knee). TE Daniel Imatorbhebhe (hip flexor) also participated in the first half of practice.

- Helton announced that the team will release the first official two-deep depth chart this Sunday.

- This was the first practice of mock game week as the Trojans began installing for the season opener against Western Michigan.

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