He was replaced in the bottom of the ninth by Elian Herrera in right field. He was unsure whether he could play Sunday.
"You know how these things are, kind of day to day," he said. "We'll see how it goes tomorrow."
The intercostal muscles are several groups of muscles that run between the ribs. Braun has had strains of the oblique muscles near the intercostal muscles in the past.
The Brewers beat the Cubs, 5-3, but the night was marred when Braun accidentally hit Segura in the face while swinging his bat in the dugout in the middle of the first inning. Segura fell to the ground and didn't initially move and required stitches near his eye.
"You never want to see something like that, you know?" Braun said. "It breaks your heart a little bit, and obviously it's never something that's done intentionally.
"Whenever you're involved in a situation like that, I think it puts life in perspective and you realize how insignificant baseball is," he said. "Thank God we heard he's OK. It could have been a lot worse or a lot worse places he could have been hit."
The Brewers could be without three players Sunday if Braun and Segura can't play. Catcher Martin Maldonado is serving a five-game suspension for his part in a bench-clearing episode against the Pirates last weekend.
Braun is batting .318 with six home runs and 18 RBIs in 22 games.
Joe DiGiovanni is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.