Robertson finished with 9-of-12 shooting from the field for the Warhawks (8-11, 4-4 Sun Belt). DeMondre Harvey added 20 points, Majok Deng had 17 points, Jamaal Samuel had 14 points with 13 rebounds and Nick Coppola chipped in 13 points. The team had a 39-26 rebounding edge over South Alabama.
Robertson scored 15 points in the first half, including a pair of 3-pointers and a dunk, to help Louisiana-Monroe to a 39-29 lead at the break.
Coppola drained a 3-pointer early in the second half to extend the Warhawks lead to 61-44 with 13:07 to play and South Alabama trailed by double digits the rest of the way.
Ken Williams scored 14 points for the Jaguars (7-12, 2-6).