Milwaukee, which entered the series with a nine-game winning streak, had one run and six hits in losing the first two games to St. Louis.
Peralta (2-0) allowed six hits and struck out three, and three relievers combined for scoreless relief.
Cardinals starter Joe Kelly (1-1) gave up an unearned run and three hits in four innings. Kelly left in the middle of the fourth inning with left hamstring tightness after trying to beat out a bunt attempt in the top half.
Milwaukee, which lost the season series 14-5 last year, went ahead in the third inning when first baseman Matt Adams misplayed Logan Schafer's leadoff bouncer for an error, Peralta sacrificed Carlos Gomez hit an RBI double to the wall in right-center, one pitch after bunting foul.
More defensive troubles helped boost the lead to 4-0 with three unearned runs in the fifth against Seth Maness. Wily Peralta reached when his two-out liner went off the glove of shortstop Jhonny Peralta for an error. Gomez walked, Jean Segura reached on an infield single, Jonathan Lucroy followed with a two-run single and Aramis Ramirez had an RBI single.
NOTES: Ryan Braun, still bothered by an ailing right thumb, was held out of the starting lineup. Braun, hitting 269, has three homers and 10 RBIs — but all the homers and seven RBIs came at Philadelphia on April 8. ... Brewers manager Ron Roenicke is pleased with defensive play of new 1B Mark Reynolds and Lyle Overbay. Brewers first basemen had 21 errors last year, including 10 by Juan Francisco. "I did hear when we first got him, through the grapevine, that he's got good hands," Roenicke said of Reynolds, primarily a third baseman for much of his career. "He doesn't have great foot speed, but range-wise, he does a nice job." ... Peralta was originally credited with a single in the fifth, but the official scorer later ruled it an error.
Link to box score: Milwaukee 5, St. Louis (9-6) 1
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