Kelly could cover for Thornburg in eighth

Hembree also an option for Sox in late innings

Kelly could cover for Thornburg in eighth

FORT MYERS, Fla. -- When the Red Sox acquired righty reliever Tyler Thornburg from the Brewers in December, the hope was that he would emerge as the primary option in the eighth inning.

But given the struggles Thornburg had in his two Grapefruit League appearances, and the fact that he's still building arm strength, manager John Farrell could go with Joe Kelly in the eighth to start the season.

"And I think there are other options here if Joe is not available. Heath Hembree has thrown the ball outstanding this camp," said Farrell. "We feel like there's depth in our bullpen. Tyler's return to us certainly would and will be a needed boost to further deepen the right-handed power group. In the interim, if it's not Tyler, yeah, Joe Kelly is the guy."

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Kelly has made a strong transition to the bullpen, which started this past July at Triple-A Pawtucket.

As for Thornburg, he threw a side session on Saturday, and Farrell hopes to get him into a Minor League game by Tuesday. A Grapefruit League game might follow in a couple days.

Thornburg pitched for the Red Sox on Feb. 25 and March 1, giving up seven earned runs over 1 1/3 innings.

"Oh, yeah, he's got to get better than what he's been. He'd tell you the same," said Farrell. "We've got to get him back to the mound. We've got to get him back comfortable in his delivery. We can't assume what has taken place last year is automatically going to happen. He and we have work to do to get back to that level."

Ian Browne has covered the Red Sox for since 2002. Follow him on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.