The Astros will go with a match-up based approach to their bullpen roles for now. Hader will undergo more testing on the sore shoulder.

Hader is the eighth pitcher to join the Astros’ current injured list, which includes starters Luis Garcia and Lance McCullers Jr. Position players such as Yordan Alvarez, Jake Meyers and Isaac Paredes are also out with various ailments.

Hader, 31, has pitched just three times in August, with his most recent appearance (on Aug. 8) doubling as his seventh this season in which he's logged four or more outs. He's been highly effective overall, tallying a 2.05 ERA (202 ERA+) and a 4.75 strikeout-to-walk ratio.