Upon walking into the dugout after a perfect fourth inning, Detroit Tigers starter Spencer Turnbull met with athletic trainer Doug Teter and manager AJ Hinch.
Turnbull, 28, did not return for the fifth inning. He left Friday's game against the Chicago White Sox with right forearm tightness. To end the fourth, he won a 12-pitch battle against rookie slugger Yermin Mercedes, ending the at-bat with a swinging strikeout.
The severity of his injury and timetable for his return remain unclear.
Turnbull cruised through Chicago's lineup over the first four innings, allowing one run on two hits.