The White Sox placed starter Michael Kopech on the 15-day injured list with right shoulder inflammation, the team announced Saturday.
Kopech was Sunday's probable starter. The Sox recalled right-hander Davis Martin from Triple-A Charlotte in a corresponding move.
It's tough news for the White Sox in their race for the AL Central crown. Kopech has been a steady presence in the rotation this season, holding a 3.54 ERA in 119 1/3 innings. He's made 25 starts, tied for a career high at any professional level.
"We're going to see where he's at in seven days," acting manager Miguel Cairo told reporters in Detroit. "Play catch and see how he feels. Hopefully he comes back. He's going to come back this year."
General manager Rick Hahn told reporters in Detroit imaging on Kopech's shoulder showed no signs for long-term concern. But based on the calendar, it's unclear if the right-hander will return before the end of the regular season.
The Sox have 16 games remaining after Saturday. They entered the day four games back of the Guardians in the AL Central and five games behind in the loss column.