BOSTON -- Red Sox closer Koji Uehara left Tuesday's 4-0 win over the Giants with a right pectoral strain and will be re-evaluated Wednesday.
Uehara struck out Brandon Belt, then issued a ball to Buster Posey before walking off the mound and signaling to the dugout.
Uehara said after the game that he felt something before the strikeout pitch to Belt.
"It's some muscle soreness that I feel," Uehara said through a translator. "I'm just praying that it's not that serious."
Uehara's injury has the potential to be a big blow to the team's bullpen. With Craig Kimbrel on the disabled list with a left knee injury, Uehara has been acting as the team's closer, converting his last five save opportunities.
Right-hander Junichi Tazawa, who's on the disabled list with a right shoulder injury, is expected to return to the bullpen as early as Friday.
Before Tuesday's game against the Giants, Farrell mentioned that right-hander Joe Kelly, who's been dominant with Triple-A Pawtucket since his demotion June 1, will move to the bullpen upon his return. That move could be expedited depending on the severity of Uehara's injury.
Right-hander Brad Ziegler, who was recently acquired from the D-backs, had 18 saves while with Arizona.
"As we've had to go to other guys to step up, we'll look to do that. I can't tell you at this point how much time Koji will miss," Farrell said. "Taz is soon to return to us, to give us a another quality arm that's a proven late-inning guy. With Brad here, again not knowing how long Koji will be down, we've got other options to go to to close out ballgames."