Long hit 10 of 13 shots and went over 1,200 rebounds (1,213) for his career in getting his 10th double-double of the season and 62nd of his career.
The Ragin' Cajuns (6-8, 2-3 Sun Belt) led 38-35 at the half and pushed the margin to 15 on a Devonta Walker free throw midway through the second half. Mike Hughes made 3 of 4 free throws to put the Eagles (5-10, 1-4) within seven with 1:33 to play, but three different players made a pair of free throws in the last 63 seconds to secure the win.
Tookie Brown led Georgia Southern with 20 points.
The Ragin Cajuns shot 47 percent, going 6 of 21 behind the arc. The Eagles shot 36 percent but was 1 of 14 on 3-point attempts.