Marli Hayward scored in the 57th minute to push VWC (10-4-3, 7-0-3 ODAC) past Shenandoah (13-6, 7-3).
The loss puts Shenandoah into a fourth place tie with Roanoke with SU earning the No. 4 seed based on the five-point tiebreaker. The Hornets will host the Maroons on Wednesday at 6 p.m.
Virginia Wesleyan outshot SU 9-4, including 4-1 in the second half, and took three of the game's five corner kicks.
Hornets goalkeeper Erin Septer had six saves.
"This was a disappointing end to the regular season," SU coach Liz Pike said. "Hopefully this is a wakeup call for us now that it is tournament time."