The Golden Eagles scored a run in the bottom of the 15th inning, handing the Blue Jays their first SLIAC loss on Sunday.
Westminster (9-5, 4-1 St. Louis Intercollegiate Athletic Conference) led 4-2 to start the bottom of the ninth inning, but Spalding plated two runs to extend the game.
Golden Eagles left fielder Austin Drake singled in second baseman Drew Beckmann for the winning run.
Blue Jays sophomore Jake Lund took the loss, giving up an earned run on three his, while walking one in 3 1/3 innings of work. Junior Will Miller threw the first nine innings, striking out eight and giving up four runs (one earned) on nine hits, while walking one.
Senior second baseman Cam Backes was 2-for-4 with an RBI, a double and a run scored as Westminster was outhit 14-9. Sophomore designated hitter Connor Hager was 2-for-6 with an RBI and a run scored.
Junior Deion Hughes struck out 10 batters as the Blue Jays rolled to an 11-1 rout in Sunday's opener. Hughes (4-0) allowed an earned run on three hits and no walks and was 2-for-2 with two RBIs and a run scored at the plate.
Backes finished 2-for-4 with an RBI and two runs scored, while freshman shortstop Chris Asher went 2-for-4 with two RBIs. Junior third baseman Tyler Branneky was 1-for-4 with two RBIs and a run scored as Westminster racked up 10 hits.
The Blue Jays begin a three-game SLIAC series at Webster at 5 p.m. Friday. The series concludes with a doubleheader on Saturday, with games scheduled to begin at 2 and 4:30 p.m., respectively at Saucier Field in Fulton.