Boston Red Sox reliever Koji Uehara left the mound due to muscle pain on Tuesday, when he retired one batter in the ninth in a 4-0 win over the San Francisco Giants.
Uehara struck out Brandon Belt looking to open the inning. After his first pitch to former MVP Buster Posey, Uehara began rubbing the right side of his chest and left the mound at Boston's Fenway Park.
"From around the fourth pitch to Belt, I felt muscle pain that was a little more intense than usual," said Uehara, who threw seven pitches before making his exit. "If it gets any worse than this, that's a problem.
"I think it will likely be OK. I've felt some stiffness since the All-Star break.
Meanwhile, fellow reliever Junichi Tazawa is expected to return from the disabled list on Friday, Red Sox manager John Farrell revealed, saying the right-hander was able to execute all his pitches and that he would be activated after a final evaluation on Wednesday.