The Hornets (29-10) took game one of this best-of-three series by scoring three runs in the first, two in the third and five in both the sixth and eighth to dominate the Tigers (17-20).
Senior Colin Morse (6-3) went the first eight innings, allowing two runs (one earned) on three hits and six walks.
Morse also struck out eight.
Shenandoah had 15 hits in the win with junior Luke Nussman hitting home runs in the first and eighth and freshman Henry Delavergne connecting for a grand slam home run five batters after Nussman's second dinger.
Nussman's first home run, a shot to right center, gave SU a 3-0 lead with one out in the bottom of the first. Grant Thompson and Tristan Baker reached on a hit batsman and a walk before Keegan Woolford was retired via strikeout.
Nussman then ripped a 1-0 Harrison Moncure offering for the 2015 ODAC Championship banner in right center to give the Hornets the lead for good.
After H-SC made it a game with two runs on three walks and an SU error in the second, Chase Smallwood had a two-run single down the right field line to extend the Shenandoah lead out to 5-2.
Smallwood finished his day 4-for-5 with three RBI while Nussman had four RBI on three hits in five at-bats.
Thompson, batting leadoff, was 2-for-3 and reached base all six times he came to the plate.
Delavergne had two hits while Nick Goode had two hits and drove in a run.
Moncure (4-4) allowed allowed five runs on seven hits in 3 1/3 innings.
The two teams play game two at 2 p.m. Sunday afternoon. Hampden-Sydney will be the home game for this Bridgeforth Field contest.