Although he was diagnosed with a left hand contusion, X-rays were fortunately negative, per Todd Rosiak of the Milwaukee Journal Sentinel.
He was 0-for-1 with a sacrifice fly in his first two at-bats before heading to the clubhouse.
Cain is one of the team's most important players as someone who makes an impact in all phases of the game, which could make an extended absence especially damaging for Milwaukee.
He entered the day hitting .261 with four home runs and three stolen bases.
The 33-year-old is a catalyst on the offense and a quality defender, which means there will be a drop-off with whoever replaces him. Ben Gamel replaced him in Sunday's game and could see extra playing time in the outfield, while Christian Yelich is also capable of sliding over to center field if needed.
Still, the team will hope Cain is able to return soon.
The outfielder is in his second year with the team after signing a five-year deal, and he certainly lived up to his billing in 2018. Cain finished with a .308 batting average, .813 OPS, 10 home runs and a career-high 30 stolen bases.
It was the fourth time in five years he posted at least a .300 batting average.
He also finished in the top 10 in MVP voting for the second time in his career, becoming one of the most reliable players in the league at his position when healthy.