Astros manager Joe Espada said that Pena is out of the lineup for Monday's game against the Twins due to left leg discomfort, Chandler Rome of The Athletic reports.
Pena has missed time this season with right hamstring issues, but it's his other leg that's bothering him this time. He's being evaluated by team doctors, and more could be known about his condition later Monday. Nick Allen (hamstring) was activated from the 10-day injured list Monday and will start at shortstop and bat eighth as a replacement in the lineup for Pena.