Sheets yielded one hit and a walk while striking out three. Valerio De Los Santos pitched a perfect inning before Curtis Leskanic gave up a run in the sixth. Mike DeJean walked one in a scoreless seventh to earn his second spring save.
Mark Budzinski and Eddie Perez gave the Brewers a 2-0 lead in the fourth inning with run-scoring singles.
Padres starter Adam Eaton gave up both runs and three hits in five innings. He struck out four and walked two.
Roberto Kelly drove in San Diego's lone run in the sixth.