FIU led 40-33 at the 12:05 mark before FAU took a 57-55 led on Solomon Poole's 3-pointer with 2:31 remaining. Diaz answered with four free throws to give FIU a 59-57 lead with 1:18 to play. Diaz then had a block, defensive rebound and assist to Daviyon Draper, who hit a jumper to make it 61-57 with 13 seconds left.
Poole drained his fifth trey to pull FAU within 61-60 with 5 seconds to go. Tashawn Desir made one of two free throws to seal it for FIU.
Dennis Mavin added 16 points and six assists for FIU (8-6, 1-0).
Poole had 22 points on 8-of-19 shooting and four steals to lead Florida Atlantic (7-5, 0-1).