Onochie Ochie and Daniel Grieves poured in 14 points each and Zay Jackson had 13 points and seven assists for SE Louisiana (3-8), which shot 56.6 percent from the floor and snapped a three-game skid with the win. Grieves also hauled in seven rebounds.
The Lions took control with a 21-2 run that stretched across both sides of the intermission and was capped by Upson's dunk that made it 50-32 with 18:13 left.
Winthrop (4-6) narrowed the gap midway through the second half and closed within two after Keon Johnson's 3-pointer made it 65-63 with 6:35 to go. But SE Louisiana responded with three straight buckets from Ochie to pull away and seal the win.
Keon Moore led the Eagles with 16 points.