Thornton leaves with oblique 'issue'

BOSTON -- There was the Tommy John surgery before he made it to the big leagues in 2002, and from time to time thereafter, some soreness in his left elbow. He also was sidelined with a herniated disc in his back.

But beyond that? “I never had injuries, hardly, period,’’ Red Sox reliever Matt Thornton said Sunday.

That’s why he was taken by surprise in the eighth inning when he felt a pain in his right side, bad enough that he had to come out of the game after just six pitches.

“I felt a little cramp at first, then it got worse,’’ Thornton said. “The last pitch got me pretty good.’’

Manager John Farrell said it was a “right oblique issue.’’ Thornton said he hoped the injury was minor, but couldn’t say with any certainty. He’ll be checked again by the Red Sox training staff after the team arrives in Houston for a three-game set against the Astros.

“I think I should be OK and it’s minor,’’ he said, “but I never had anything like it before, so no idea.

“It’s one of those things,’’ the 36-year-old reliever said. “I think I take care of myself, eat right. Just a freak thing.’’

One of Boston’s three other left-handed relievers, Drake Britton, finished the inning for Thornton, striking out Didi Gregorius, the batter when Thornton left, giving up a ground-ball base hit to A.J. Pollock, then retiring Aaron Hill on a fly ball and making a nice play on Paul Goldschmidt’s comebacker to end the inning.

Britton has not been scored upon in his first seven appearances, spanning nine innings. He is the first pitcher ever to begin his Sox career with seven scoreless outings, according to the Elias Sports Bureau. Koji Uehera pitched a scoreless ninth.

“Drake Britton once again, against the heart of their order -- all right-handed -- doesn’t back away from a challenge,’’ Farrell said. “He’s poised.

“An excellent job on his part, and Koji continues to do what he’s been doing most of the year.”

If Thornton is forced to miss any significant time, the Sox have a safety valve in left-hander Franklin Morales, who is on a rehab assignment with the PawSox and has thrown 4 1/3 perfect innings in three appearances to date.