FIU 41, Akron 38, OT
Medlock, who threw for 348 yards and two touchdowns in his debut last week, opened the scoring with a 29-yard touchdown run.
Williams threw his fifth touchdown to Marquelo Suel to give Akron a 38-35 lead with 1:53 to play but FIU's Jack Griffin connected from 30 yards out as time expired.
Griffin's 41-yarder in overtime sealed the victory for the Panthers (1-1).
Safety John Cyprien led the FIU defense with 11 tackles. The junior, who had nine tackles last week, now stands 10 tackles shy of tying the school-record of 302 total tackles.
Williams led Akron with 313 yards passing.