"Just for this run, we'll have six men," Counsell said. "Then we'll see where we stand."
The Brewers' rotation situation could look different by 3 p.m. CT on Friday, the deadline for teams to trade players without first exposing them to waivers. Young, homegrown pitchers Peralta, Jimmy Nelson and Taylor Jungmann are all but certain to stay, but the Brewers could move Lohse (a free agent at season's end) or Garza (in the second season of a four-year, $50 million contract) if another team is interested, and Mike Fiers has been scouted by rival clubs. Brewers GM Doug Melvin has said he's reluctant to move Fiers, who has been productive this season while essentially earning the league minimum salary, and is under club control through 2019.
Peralta said he was "very excited" to pitch in the big leagues for the first time since suffering a strained left oblique during a May 22 outing in Atlanta. At the time, he thought he'd miss a start. Instead, he missed more than two months, but returned to pitching shape by making a trio of Minor League rehabilitation starts in recent weeks.
"I finally feel 100 percent," Peralta said. "No pain, I don't feel anything. It's good to be back with the team. …
"It's frustrating to be out that long, watching the guys every five days out there from the dugout, not being able to be out there. It's frustrating, but I got through it and I'm glad to be back."
He threw 74 pitches in his most recent start for Double-A Biloxi on Tuesday. Typically, a pitcher building up his pitch count advances 15-20 pitches per start, moving Peralta comfortably into the 90-pitch range against the Giants.
"He'll be fine for his next start," Counsell said. "You'll watch him, obviously, but that's plenty of pitches to get deep in a game."
Adam McCalvy is a reporter for MLB.com. Follow him on Twitter @AdamMcCalvy, like him on Facebook and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.