Pena was diagnosed with a fracture in the tip of his right ring finger Thursday, Matt Kawahara of the Houston Chronicle reports.
Pena suffered the injury while playing in a World Baseball Classic exhibition game for Team Dominican Republic on Wednesday. He will now miss the WBC, but his status for Opening Day will depend on how he checks out during his re-evaluation in two weeks. If the 28-year-old ends up missing the first portion of the regular season, Nick Allen could step in to start at shortstop for the Astros, or perhaps Carlos Correa could shift back to short.