Boston Red Sox reliever Carson Smith suffered a subluxation of his right shoulder when he threw his glove in the dugout Monday night, president of baseball operations Dave Dombrowski told reporters Tuesday.
Smith was placed on the 10-day disabled list Monday, but Dombrowski said there was no timetable for his return.
Dombrowski called the injury "unfortunate" and said Smith is seeking a second opinion.
"It's got the potential of being a major injury," he said.
Smith said he's concerned.
"Any shoulder injury isn't a good injury," the right-hander told reporters. "Elbow's one thing, but a shoulder is something you don't mess with. Yeah, I'm concerned."
Smith allowed an eighth-inning home run to the Athletics' Khris Davis in Boston's 6-5 loss Monday night. When Smith left the mound he threw his glove in frustration, causing the injury.
Smith is 1-1 with a 3.77 ERA and 18 strikeouts over 14.1 innings pitched.
"I think fatigue played a factor," he said. "My shoulder just couldn't handle it. I think my shoulder is tired in general just from pitching. I've thrown a lot lately and I think my arm was just tired."
Left-handed pitcher Bobby Poyner has been called up from Triple-A Pawtucket.
Also Tuesday, Boston acquired minor league left-hander Josh Taylor from the Arizona Diamondbacks, completing the March 24 deal for infielder Deven Marrero. The 25-year-old has been assigned to Double-A Portland.