"I don't know what happened," said Brown, who dove for a ball in the first inning in an 11-2 loss to the Reds. "We're going to get an MRI and see exactly what's going on. I don't think it's anything major at all."
But Brown added, "I felt some pain immediately. Once I took a couple of swings, I really felt it."
He left the game in the fourth inning.
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.