Fairfield started off its offensive effort in the top of the first inning as MAAC Rookie of the Year Lauren Liseth hit a two-run homer over the center field fence.
Marist tied it at 2-2 in the bottom of the third as junior left fielder Ashley Corriss doubled down the right field line to bring in freshman second baseman Haley Birnbaum and junior centerfielder Caitlin Schell scored on a sacrifice fly by sophomore designated player Sarah Carmody.
The Stags pulled ahead for good in the top of the fourth with senior first baseman Kristina Lingo scoring on a single to center field by junior shortstop Laura Carta.
Sarah Minice, the MAAC Pitcher of the Year, improved to 18-8 on the season with the win, allowing five hits and striking out seven batters. Emily Osterhaus dropped to 15-9 on the season, giving up nine hits while fanning four batters.
Fairfield will play the winner of today's Game 5 on Saturday, May 14, at noon.