Stanton looked like he was attempting to check his swing on the pitch, which ended up running in on him, rising and hitting him square in the face. A long delay ensued at Miller Park in Milwaukee before Stanton was carted off the field on a stretcher.
The Marlins said Stanton suffered a laceration on the left side of his face. He had X-rays and a CT scan performed at a local hospital.
Stanton was replaced by Reed Johnson, Fiers hit with his very next pitch. That sparked both benches to clear, and Marlins manager Mike Redmond was ejected.
"One of the most gut-wrenching nights in Marlins history," Marlins broadcaster Rich Waltz said. "Not for the decision in the ballgame but the events of the fifth inning."
Here's a Vine of the pitch that hit Stanton:
The Marlins' Twitter account immediately sent out words of encouragement to Stanton: