Rondon will be recalled by the Cardinals on Saturday, Jeff Jones of the Belleville News-Democrat reports.
Rondon began the year with Triple-A Memphis and posted a 5.32 ERA and 1.47 WHIP in 23.2 innings across five appearances (four starts). Although the right-hander served mainly as a starter in the minors, he'll likely make his major-league debut out of the bullpen.