Pena (knee) is not in the lineup for Sunday's game against the Mariners, Chandler Rome of The Athletic reports.
The 28-year-old shortstop departed Saturday's 8-7 loss due to right posterior knee tightness. According to Matt Kawahara of the Houston Chronicle, manager Joe Espada said Sunday that he didn't have an update available for Pena, who should be considered day-to-day as he continues to be evaluated. Nick Allen will step in at shortstop Sunday for the Astros.