The blister that has plagued him of late felt the worst it's been all season on Sunday.
"You know, I walked a lot of people, but I think I made big pitches when I needed to," Peralta said.
St. Louis remains two games up in the division, but now has two teams to fend off in second after the Reds defeated Pittsburgh 11-3 to pull into a tie with the Pirates.
Errors by third baseman David Freese and starter Joe Kelly (9-5) helped contribute to the two Milwaukee runs in the second.
Kelly hesitated on what could have been an inning-ending double play in the first after getting Carlos Gomez to bounce sharply back to the mound with runners on first and third. That allowed a run to score from third.
Aoki had led off the first with a single and came home on an RBI single by Aramis Ramirez with one out. Aoki then reached on an RBI double in the second before scoring after Kelly threw away a sacrifice bunt attempt by Scooter Gennett.
"My stuff felt good," Kelly said. "Obviously, me throwing away a ball didn't help. Just one of those games and that kind of stuff happens."
Kelly went seven innings, allowing seven hits and six runs — three of them unearned.
NOTES: LF Matt Holliday was scratched from the starting lineup with back spasms. ... St. Louis has a major league-leading 34 wins from rookie pitchers this season, their most since also getting 34 in 1952. ... Manager Ron Roenicke thinks SS Jean Segura will be available for pinch-hitting duties for the Brewers' three-game set starting Monday in Atlanta. Segura, the NL leader in steals with 44, has been sidelined since Wednesday with a strained right hamstring. ... LF Khris Davis was out of the lineup Sunday due to a nagging wrist injury, but is also likely to return to action in Atlanta.
Cut pounds of stomach fat every week by using this 1 weird old tip.