Jackie Bradley Jr. replaced the 35-year-old before the top of the fifth inning. Cain was 0-for-1 with a walk before exiting.
Injuries have plagued Cain throughout the 2021 season. He's been on the injured list three times in 2021, all with leg issues. Cain's most recent concern was a strained hamstring in June.
"It's definitely been a tough start to the season for me," he told reporters. "A lot of stop and start for me this season, starting from spring training on to this point. I don’t think they're related, but at this point, who knows?"
The Brewers have managed to stay in the playoff hunt without Cain for most of the season and are on the precipice of clinching the National League Central title.
When he's been in the lineup, Cain has been understandably rusty, slashing .253/.328/.402 with eight home runs and 35 RBI entering Saturday.