With the loss, Saint Mary's drops to 6-15 while CSUS improves to 12-8.
The Gaels took advantage of three walks and three hit batsmen in the first inning and scored six runs. Nikko Saenz had the big hit with a two-RBI double. DonAndre Clark had SMC's other base hit that inning, driving in a run.
CSUC chipped away with two in the first, one in the second and three in the sixth.
The Gaels added one run in the fifth inning but the Hornets scored two in the seventh and another in the eighth.
Saint Mary's did not go quietly however, loading the bases with one out in the eighth inning. A fly out and strike out ended the rally and SMC still trailed by two.
The Gaels loaded the bases with no outs in the ninth inning as Cole Norton, Shawn O'Brien and Darian Ramage all singled to load the bases. CSUS got out of the jam with a fielders choice resulting in a force out at the plate for the first out. The next two outs were recorded on fly balls as CSUS escaped with the win.
Anthony Gonsolin (0-1) took the loss while Ty Nichols (3-1) earned the victory.
Mark Anderson got the start for the Gaels going 1.0 innings and allowing two runs on one hit.
Gary Cornish went five frames while Tanner Kichler, Thomas Cortese and Patrick Keane also saw action.
Ian McLoughlin made his first collegiate start at catcher for the Gaels.
Saint Mary's is back in action on Friday when it hosts LMU in a West Coast Conference game. First pitch is slated for 3:00 p.m. in Moraga.