Gray (elbow) was activated from the 10-day injured list ahead of Friday's start at Milwaukee.
The 29-year-old missed the past three weeks with a strained right elbow, but he'll rejoin the rotation in Friday's series opener. Gray had a 2.54 ERA and 1.09 WHIP through his first five starts of the campaign, but he posted a 5.71 ERA in his previous seven outings before landing on the injured list.