Stubbs suffered a right ankle sprain during Thursday's game with Triple-A Sugar Land, Brian McTaggart of MLB.com reports.
It remains to be seen if the ankle injury will end up sending Stubbs to the injured list, but he seems likely to miss at least a game or two. He's spent the bulk of the season at Triple-A, but he has logged eight games with the Astros, recording four hits across 22 at-bats.