The St. Louis Cardinals had an intriguing doubleheader on Saturday against the Cincinnati Reds and will conclude the series on Sunday with a new face on the mound. On Saturday night, Derrick Goold of the St. Louis Post-Dispatch reported that Cardinals No. 20 prospect Brycen Mautz will make his big league debut on Sunday as the club's starter. "Brycen Mautz will start for the Cardinals on Sunday in the series finale against the Reds. It will be his major-league debut," Goold wrote. "The Cardinals are using this to set their rotation coming out of the doubleheader and ahead of needing a starting Wednesday. Matthew Liberatore, the scheduled starter, gets Monday in Milwaukee with the extra rest. All starters get that extra day now." The Cardinals Are Promoting Their No. 20 ProspectFeb 14, 2026; Jupiter, FL, USA; St. Louis Cardinals pitcher Brycen Mautz (52) delivers a pitch during spring training at Roger Dean Chevrolet Stadium. Mandatory Credit: Sam Navarro-Imagn Images | Sam Navarro-Imagn ImagesOne thing that is clear about the Cardinals is the fact that they prioritize rest of their starters. That's why earlier in the season when St. Louis had a long stretch of days without a day off, Hunter Dobbins was called up as the team's sixth starter for a brief time. This is another example of that. With Mautz getting the start on Sunday, Liberatore will have extra rest before his start on Monday in line with the rest of the rotation. For Mautz, he's an intriguing prospect. He's 24 years old and has a 2.90 ERA so far this season down in Triple-A. Last year, Mautz logged a 2.98 ERA in 25 starts down in Double-A. He's a former second-round pick who has been steadily building to this moment. Recently, Mautz is a prospect that we said isn't a household name, but fans should start to learn about. About a week later, he is now going to be making his big league debut. He's a lefty who played his college ball at the University of San Diego, before being drafted by the Cardinals back in 2022. He began his professional career in 2023 in Class-A Palm Beach and had worked his way up the rungs of the minor league ladder ever since. Now, he gets to try to help St. Louis take a series against one of its biggest rivals. It's a perfect example of why baseball is great. He was down in Triple-A and was pitching well and now is being rewarded when an opportunity opened. Hopefully, he's able to maintain his momentum from down in the minors. Add us as a preferred source on GoogleFollow