The spring evaluation period began Wednesday, and USC is off to a fast start.
Offensive lineman Frank Martin of Mater Dei High announced his commitment Thursday, a day after Murrieta Mesa offensive lineman Nathan Smith.
"I am proud to announce that I have committed to play football at the University of Southern California #FightOn," Martin wrote on Twitter.
Martin, 6 feet 6 and 285 pounds, said last month that he watched USC growing up and pretended he was Reggie Bush.
Martin is the fifth player in the 2016 class to commit to USC.
Tight end Isaac Garcia and linebackers Daelin Hayes and Mique Juarez also have committed.