Gerrit Cole was scratched just before his scheduled start against the Chicago White Sox on Tuesday.
Cole began warming up in the Houston Astros' bullpen before reporting right hamstring tenderness.
"Right before the game, as he was warming up, [bullpen coach] Josh Miller called down and told the dugout that his hammy wasn't feeling very good, and he didn't feel like he could continue," A.J. Hinch said.
Cole underwent treatment during the game and will undergo further examination on Wednesday. Hinch is hopeful that the injury is minor -- and glad Cole was forthright in his communication with the club.
"We'll get him tested even further and see where this takes us," Hinch said. "He doesn't think it's that serious. I'm glad he told us, and we hope that it's mild. It was literally a couple of minutes before the game."