"I think that's still iffy," Roenicke said, "but I'm really glad that he's feeling well."
The Brewers have had trouble with hamstrings lately. Closer Jim Henderson spent two weeks on the disabled list in late May and early June with a strained right hamstring, and starter Marco Estrada has been on the DL for nearly a month with a strained left hamstring that continues to give him trouble.
Given Peralta's importance to the Brewers' future, the club will not take any risks, Roenicke said.
"But Wily was just in the weight room getting in some work, so that tells me he's pretty good," Roenicke said. "He was out here playing catch and felt good. He felt a little bit of tightness, but other than that, pretty good.
"Talking with [head athletic trainer] Dan Wright … to put him back out there if they don't think he's 100 percent, I don't think we'll do that."
If he gets back to 100 percent, Peralta would pitch Sunday against the Mets at Miller Park. If the Brewers push him back, Tyler Thornburg would be the leading candidate to pitch in that spot.
Peralta predicted he will pitch.
"I think so," he said. "I just [did] a little stretching to loosen it up."
Estrada, meanwhile, remains in Arizona building strength. He is fine playing catch, Roenicke said, but every time Estrada tries throwing a bullpen session, he feels discomfort in his hamstring, particularly on offspeed pitches.
Until that subsides, the Brewers will not send him back out on a rehab assignment.
Roenicke was able to give a more positive update on right-hander Alfredo Figaro, who went on the DL in late June with a right ribcage strain. He is progressing "really well," Roenicke said, and could rejoin the Brewers before the All-Star break.