Cubs starting pitcher Adbert Alzolay exited Friday's game against the Marlins in the second inning with left hamstring tightness.
Cubs manager David Ross and trainer PJ Mainville checked on Alzolay after a 1-1 pitch to Isan Díaz sailed up and outside. Alzolay was flexing his left leg on the pitcher's mound before departing the game.
Alzolay was getting treatment after the game and will be reevaluated on Saturday.
The right-hander spent the previous half inning running the bases after hitting a double. He then ran to third base on a single by David Bote.
Alzolay surrendered a grand slam three batters before leaving the game. Miami loaded the bases on two singles, one on the infield, and a walk.
The five earned runs Alzolay allowed were a season high.
"That guy is so competitive," catcher Robinson Chirinos said of Alzolay. "He wants to give this team a chance to win a game.
"You could see the pain through his eyes and how he felt when he came out of the game."