Matthews will start Saturday in Toronto, which will be his MLB debut, Derrick Goold of the St. Louis Post-Dispatch reports.
Matthews was removed as an upcoming probable pitcher in Triple-A Memphis for Thursday, which hinted at his promotion. While the call-up is yet to be announced, he appears set to take a big league mound Saturday. He has been stellar in Triple-A since June hit with a 1.55 ERA across 52.1 innings. It remains to be seen whether the Cardinals will trade a player such as Dustin May at the trade deadline looms Monday to create space for Matthews.