Mayza will serve as the Phillies' opening pitcher for Saturday's game in Atlanta, Todd Zolecki of MLB.com reports.
Mayza will make his fifth start of the season, but he has yet to record more than six outs in any of his 54 appearances to date and will likely be limited to 1-to-2 innings. The Phillies don't have an obvious bulk reliever available behind Mayza, but Grant Holman hasn't been used since being recalled from Triple-A Lehigh Valley on Sept. 1 and could be called upon to pitch multiple innings once Mayza exits.