Flaherty will start Friday against the Brewers, Rob Rains of StLSportsPage.com reports.
Flaherty, who was originally lined up to pitch Thursday's series finale against the Nationals, will flip places in the rotation with Luke Weaver (finger), lining him up to start Friday's series opener against Milwaukee. There has been no word of any injury to this point. The 22-year-old right-hander owns a 3.22 ERA and 127:36 K:BB through 19 starts (103.1 innings) this season.