It's the Mustangs third win in a row, and it came in front of a record 4,427 fans at Phil Welch Stadium.
Ryker Fox whittled his league-low ERA down to 0.28 while working out of multiple jams over 6 1/3 innings in the victory over Sedalia.
The Bombers collected just three hits and four walks against Fox, but left 11 runners on base in the game.
Mustangs' starters from the last two contests, Fox and Jake Jones, combined for no runs, three hits allowed and six strikeouts in 13 1/3 innings.
St. Joseph had chances to plate runs with a total of six hits and four walks, but Sedalia's Sam Perez struck out five and only conceded one run.
The Mustangs started the fourth inning with three singles to load the bases. Brandon Huske followed by hitting into a 6-4-3 double play allowing Joe Koerper to cross the plate to put St. Joe ahead, but also ending the threat of any major damage in the inning.
St. Joe threatened with a runner reaching third in the sixth and loading the bases in the seventh, but couldn't push another run across.
Grant Gavin, Jon Pomatto and Brett Ash each came out of the bullpen to finish the final 2 2/3 innings for the Mustangs, with Ash recording his ninth save and tenth consecutive scoreless outing.
The Mustangs have now won 12 of their last 15 games, and hold a 3 1/2 game lead over Chillicothe in the North Division standings.