Berkman started on Monday night against the Cardinals after not starting in the previous three games with the same injury. He pinch hit in one of those games and says he's available for that duty in this series.
He realized his leg was probably still too tender to play when he struggled running the bases on a double in Monday's game.
Team doctor David Lintner made the diagnosis after an MRI on Monday and is requiring the slugger to wear a walking boot to help aid the healing.
The Astros are off on Thursday and Berkman says he hopes to return for Friday's game against the Mets.