Mercer totaled 11 runs in the second and third innings to run-rule Siena Baseball 13-2 in the series finale in Macon, Georgia.
Mercer (13-7) broke the game open with a six-run third inning to claim an early 7-0 lead. The Bears sent 12 men to the plate in the frame, capitalizing on three walks and three hit batsmen.
Mercer then put the game away with a five-run fourth inning, highlighted by a grand slam from Brandon Prince.
Jackson Cherry added three hits including a home run for the Bears, while Jess Ackerman tossed the first six innings on the mound with seven strikeouts to earn the win.
Siena (0-16) scored both of their runs on a two-out, two-run double by freshman
Noah Brooks in the fourth. Seven different Saints recorded one hit apiece in the defeat.
Siena returns to the Empire State for midweek action at Army West Point Wednesday at 3 p.m.