Alvarez exited Saturday's game against the Padres with an apparent leg injury, Chandler Rome of the Houston Chronicle reports.
Alvarez went down after fouling a ball off his left leg in the top of the fifth inning, and he needed some assistance to get off the field. He went 1-for-1 with a walk prior to his departure, and it's not yet clear whether he'll be available for Sunday's series finale in San Diego.