Gray was placed on the 15-day injured list with a right pectoral strain Thursday, retroactive to May 30, Betsy Helfand of the St. Paul Pioneer Press reports.
Gray exited Sunday's start against the Royals due to a sore right pectoral, but he improved in recent days and played catch Wednesday. However, the right-hander will ultimately be forced to miss several turns through the rotation. It's a discouraging setback for the 32-year-old, who posted a 1.65 ERA and 0.91 WHIP in 27.1 innings over five starts in May after returning from a hamstring injury. Yennier Cano was recalled from Triple-A St. Paul on Thursday, but it's not yet clear who will take Gray's place in the rotation.