Sousa (oblique) will begin a rehab assignment at Triple-A Sugar Land on Saturday.
Sousa opened the regular season on the injured list after suffering a left oblique strain during his final spring training appearance. It's unclear how many rehab outings he'll need, but the Astros never imagined the southpaw needing much more than a minimum-length IL stint, so he could be added to the big-league bullpen relatively soon.