Dustin Pedroia went 0-for-3 in his first rehab game for Double-A Portland on Thursday night.
The veteran Red Sox second baseman started this season on the injured list and played in just six games before leaving an April 17 game at Yankee Stadium after he felt something "pop" while running down the first-base line. He then went on the IL again with left knee irritation.
The 2008 AL MVP is batting .100 with two singles in 20 at-bats.
Pedroia flew out twice and grounded out in his three at-bats for Portland before being removed to start the sixth inning.
He's expected to take Friday off and then play again Saturday.