Tom Haudricourt of the Milwaukee Journal Sentinel reported Braun is on the DL. He aggravated the injury during Wednesday's game against the Boston Red Sox and was taken out after reaching base on a single in the bottom of the fifth.
Braun was fantastic for the Brewers last season, hitting .305/.365/.538 with 30 home runs in 511 at-bats. His 135 OPS+ was his best since 2013, per Baseball Reference. He's off to a strong start in 2017 with a .287/.374/.574 slash line.
At 33 years old, Braun has shown no signs of slowing down. He was dinged up at times last year, including a back injury suffered late in spring training and a knee injury after crashing into a wall in August.
The Brewers are starting to build a roster that could potentially make them a contender, though they could just as easily hang around .500 in 2017. Eric Thames has brought his prodigious power output from South Korea to Milwaukee, slugging .737 so far this season.
Braun is still one of the key driving forces behind the Brewers lineup. He is the rare power hitter who gets on base and hits for average. His absence will likely push Hernan Perez or Nick Franklin into the starting left field job for the time being.
Braun has become less durable in recent years, which tends to happen when players reach the age of 30. He missed 27 games last season after playing in 140 in 2015, so the Brewers have to be cautious with the former National League MVP to maximize his value.