Infielder Brock Holt, who was acquired by the Red Sox back in December along with Joel Hanrahan in a trade with the Pirates, is the likely candidate to replace Diaz on the roster for Saturday's game against the Angels.
With shortstop Stephen Drew on the disabled list until at least the day before the All-Star break, Holt should get a chance to show the Sox what he can do over the next few days.
In 60 games with Pawtucket, Holt is hitting .263 with one homer and 18 RBIs.
Holt can play second, short and third. This would be his first Major League stint with the Red Sox.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.