Demon starter Colin Bear (3-6) who went 4.1 perfect innings and five no-hit frames took the loss. He threw a total of 5.2 innings and allowed three runs, two earned, on three hits with one walk and three strikeouts.
Matt Pittari took his first win of the season pitching one third of an inning, and Lopez continues to lead the conference in saves taking his 16th which is two short on the SLC record.
Northwestern State (16-26, 11-13 SLC) remains in seventh place in the SLC standings.
The Lions improved to 30-15 overall and 15-9 in conference.
NSU jumped out to the early lead scoring both of its runs in the fourth when Nick Hinojos hit an infield single and was advanced to second when Todd Wallace hit a grounder to third that was botched by SLU second baseman Brock Hebert.
Wallace and Hinojos both advanced when Sam Roberson threw the baseball into left field trying to gun down Hinojos at third on a wild pitch.
Nick Purdy singled to shallow left field to score Hinojos. With Wallace on third and one out, Matt Burns attempted to put down a bunt for a squeeze, but missed and left Wallace, who eventually scored on an error by the catcher, in a run down situation.
Southeastern scored three runs in the top of the sixth innings on three hits and two errors. The go ahead run crossed the plate on an error from right fielder Kevin Sanford. The Lions added another in the top frame of the eighth.
Drew Helenihi pushed his consecutive games on-base streak to 25 when he singled in the third inning.
Carson Goldsmith took the mound in the sixth and pitched 1.1 innings, but was taken out in the eighth after giving up two singles. The run given up in the eighth was credited to him.
Joe Scanio pitched perfect ball both the eighth and ninth innings.
NSU travels to Central Arkansas for another SLC series starting at 7 o'clock Saturday.