Hunter, sidelined with a left groin strain, is 1-1 with a 6.06 ERA and leads the team with 11 saves in 14 opportunities. He hasn't pitched for the Orioles since May 20.
Hunter had one rehab assignment, throwing 11 pitches in a scoreless inning with two strikeouts and a hit batter for Single-A Delmarva on Saturday.
''I felt good,'' Hunter said. ''I was able to throw the ball over the plate for the most part except for the last guy. I was happy with it. Was able to throw some pitches where I wanted them. It was good.''
To make room, Baltimore optioned right-hander Evan Meek to Triple-A Norfolk. Meek was 0-2 with a 6.39 ERA in 13 appearances.