Pena (knee) will begin a rehab assignment at High-A Palm Beach on Friday, Jenifer Langosch of MLB.com reports.

EDGE Analysis

Pena's season has been filled with injuries, so much so that he's only played in four games. During his limited action, he's managed to go just 1-for-8 at the plate. Upon his activation from the DL, Pena will return to his role as Yadier Molina's backup.