Braun, who has dealt with nagging back issues over the past few weeks, initially injured himself during Sunday's regular-season finale and at some point was unable to continue Wednesday night.
Braun, 36, appeared to aggravate the ailment while banging against the wall after catching a deep fly ball off the bat of Los Angeles Dodgers catcher Will Smith to end the second inning. Braun batted in the next half-inning and struck out swinging, then he was replaced by Tyrone Taylor when his spot came up again in the fifth.
"I don't know what tomorrow will bring," Counsell, speaking after his team's 4-2 loss, said of Braun potentially serving as the designated hitter against Clayton Kershaw in Game 2. "You can call it day-to-day. I think everybody is at this point."
Braun, who might be finishing up his final season with the Brewers, batted .286/.324/.635 in September.