Craig Kimbrel,Robinson Chirinos

Boston Red Sox's Craig Kimbrel examines a new ball after giving up a three-run home run to Texas Rangers' Robinson Chirinos, left, during the ninth inning of a baseball game in Boston, Tuesday, July 5, 2016. The Rangers won 7-2. (AP Photo/Michael Dwyer)

(Michael Dwyer)

BOSTON -- Boston Red Sox closer Craig Kimbrel was unavailable to pitch during the team's series opener against the Tampa Bay Rays after he experienced left knee discomfort before Friday night's 6-5 win.

According to Red Sox manager John Farrell, Kimbrel complained of discomfort after shagging fly balls during batting practice.

Kimbrel was sent for an MRI Friday evening, and the team will not have an update on his condition until tomorrow.

"Everything we did early he was fine, but then he felt something while the running was taking place -- unfortunately in BP when he shagged," Farrell said.

Farrell went on to say that Kimbrel will likely miss the All-Star Game.

"I'd probably venture to say he's not going to be available for that," Farrell said.

In his first year with the Red Sox, Kimbrel has gone 1-3 with a 3.55 ERA and a 1.09 WHIP while picking up 17 saves in 19 opportunities. Most of his struggles this season have come in tie games or in non-save situations.

Friday evening, the Red Sox turned to Koji Uehara in the ninth inning of a two-run ball game with the Rays. Uehara gave up a solo home run to Evan Longoria, but the Red Sox held on for a 6-5 win.

The Red Sox were also without reliever Junichi Tazawa, who has been dealing with shoulder tightness since his outing against the Los Angeles Angels of Anaheim on July 3. In that appearance, he gave up two runs on three hits in one inning of work.

Tazawa has not had a MRI for the discomfort and, as of Friday night, was not scheduled to have one.