Former Golden Bear tied for 28th place after 36 holes.
Hahn's three-under par 69 has him tied for 26th while his chest bump is adding to his popularity.
Desimone inducted into NCGA Hall of Fame; Hahn, Homa and Wi in Pro-Am.
Michael Weaver, Brandon Hagy and JoŽl Stalter are among 30 collegiate golfers up for prestigious honor.
Brandon Hagy and JoŽl Stalter share individual medalist honors.
Golden Bears trail second-round leader USC by two strokes.
Golden Bears back in action for first time since October with 21 wins over last 33 stroke-play events overall.
Former Cal player and 2012-13 collegiate player of the year opens with two-under par 70 at Farmers Insurance Open.
Cal senior tied for third among nine Americans in the field.
Cal senior moves up three spots Thursday and will head into Friday's final round five shots out of the lead.
Cal senior moves up six spots following even-par 72 in Wednesday's second round.
Cal senior opens event with one-over par 73.