Cubs manager Joe Maddon said after the game Fowler was sore, but the initial prognosis from team athletic trainers could be worse.
"Not bad, not awful, just sore," Maddon said. "But we have to check it out to make sure."
Fowler will undergo an MRI on Sunday.
Fowler has been a vital part of the Cubs' success this season, hitting .290 with seven home runs and 28 RBIs. He's also the leading National League vote-getter among outfielders in the latest Esurance MLB All-Star Game Ballot update.
So though Fowler's injury is concerning, Maddon also found a way to keep the mood light.
"He also wants to let the fan base know to continue to vote for him for the All-Star Game," Maddon said.
Cody Stavenhagen is a reporter for MLB.com based in Chicago.