Viane Talamaivao of Corona Centennial High signed with the Trojans on Wednesday.
Talamaivao, 6 feet 3 and 330 pounds, is part of a class that includes Bellflower St. John Bosco's Damien Mama and Los Angeles Loyola's Chris Brown.
Toa Lobendahn and Jordan Austin are already attending classes at USC.
"Big V is a strong powerful guy," Sarkisian said on USC's website.
"Physically, he is ready-made to come in and play for us."