Upton had 12 points, Duplessis added 11 with four assists and Jackson chipped in 10 and had six assists for Southeastern Louisiana (8-16, 5-6 Southland Conference).
The Lions made 8 of 15 from long range and shot 53.5 percent from the field (23 of 43) while limiting Nicholls to 15-of-42 shooting (35.7 percent). Southeastern scored 30 points in the paint, while holding the Colonels to 18 points.
The game was tied at 51 with 4:11 left. The Lions had a 9-2 run to lead 60-53 with 1:09 remaining. Richie Lewis made four straight free throws to close to 60-57 but Dylon Maggio nailed a trey to seal the victory.