Jason Heyward exited Saturday's Giants-Cubs game after a scary collision while running the bases.
Giants shortstop Brandon Crawford's knee struck Heyward's head as the Cubs outfielder slid into third base in the fourth inning.
"That was a tough collision," acting manager Andy Green said. "It’s two strong guys running into each other pretty hard there. Took a knee to the head. Definitely got his bell rung."
Heyward reached on a single and was advancing to third on a David Bote groundball into the shortstop hole. Crawford sprinted over to cover a vacated third base and caught a return throw from first baseman Brandon Belt.
Crawford collided with Heyward as he attempted to tag and hurdle him.
Heyward remained on the ground for several minutes while being tended to by the Cubs training staff. He was assisted off the field by the training staff.
"He’s definitely going to be watched closely over the next 24 hours and find out where he’s at," Green said.
"I don’t think there’s a formal diagnosis at this point in time, but somebody we’re going to monitor very close and make sure J is doing OK."
Cubs pitcher Adrian Sampson pinch ran for Heyward. Ian Happ took over in right field, moving from left, and Nick Martini remained in the game to play left after pinch hitting in the fourth.