Thompson will make his first career start Monday against the Pirates, Katie Woo of The Athletic reports.
Thompson made his big-league debut in early June against the Cubs, allowing one run across four innings of relief work. The extent to which Monday's opportunity is an audition for a permanent rotation role isn't entirely clear, as the Cardinals needed an extra starter ahead of Tuesday's doubleheader and will be getting Jack Flaherty back from his shoulder injury fairly soon. That said, the 2019 first-round pick comes with a fair amount of prospect pedigree and struck out 30.1 percent of the batters he faced across 10 starts for Triple-A Memphis this season, so it's very possible he makes his case to remain in the rotation.