The victory means that the Hornets (11-4, 8-2 ODAC) have earned a bye into the tournament semi-finals.
SU will host the winner of the No. 3 vs No. 6 game on Saturday, April 27 at a time to be announced.
The tournament championship will be on Saturday, May 4 on the campus of the highest-seed remaining in the tourney.
Against the Marlins (4-12, 3-7), coach Lindsey Lutz' club scored the opening eight goals of the game to seize total of the contest. Senior Amy Rollins had three of these goals, including the one at 18:51 that proved to be the game-winner.
Rollins' classmate, Corrinne Kosmowski, added two goals in this opening spurt.
After VWC tallied for the initial time, at 6:48, Shenandoah sandwiched a 4-0 run around the halftime break to lead 12-1 with 22:53 remaining.
The lead reached 11 goals on one more occasion, with 47 seconds remaining, before the Marlins scored the game's last two goals to provide the final margin.
The Hornets outshot their hosts 30-24, had a 26-21 advantage in groundballs and earned 14 of 23 draw controls.
Shenandoah goalie Ashley Cross made 12 saves.
Sophomore Samantha Sisson had a team-high six points on two goals and four assists while Rollins had four goals and Kosmowski three.
Junior Samantha Donaghy had three goals and one assist.
Official pairings for the tournament will be announced this evening.