Glasnow has been placed on the 10-day injured list. He left his start against the visiting New York Yankees in the sixth inning Friday.
The 25-year-old motioned to the Rays’ dugout after striking out Gleyber Torres on a curveball. Tampa Bay’s athletic training staff went to the mound and briefly chatted with Glasnow, who quickly walked off the mound and into the Rays’ clubhouse.
“I don’t really know what’s going on right now,” Glasnow said after the game. “I’m just going to be optimistic. It wasn’t a pop or anything crazy. I just felt tightness for a couple pitches.”
The team said Glasnow will be shut down from throwing for seven to 10 days.
Along with Glasnow’s IL move, the Rays activated catcher Travis d’Arnaud, whom Tampa Bay acquired in a trade Friday, and recalled shortstop Andrew Velazquez from Triple-A Durham. Catcher Nick Ciuffo was optioned to Durham.
Glasnow, who had been the major league leader in wins and ERA entering Friday, suffered his first loss of the season during Friday’s 4-3 defeat.
D’Arnaud, a former New York Mets catcher, made only one pinch-hit appearance with the Dodgers after signing with them Sunday. He was traded to Tampa Bay for $100,000.
The Associated Press contributed to this report.