Mack sustained a torn left Achilles' tendon during practice Tuesday, Dani Sureck of the Cardinals' official site reports.
Mack had just signed with Arizona on Friday, but his hopes of playing in the NFL this season are effectively over. The 27-year-old previously suffered a torn right Achilles' tendon in Week 1 of the 2020 campaign, and he's struggled to find a consistent role in the league ever since. Mack will now work to get healthy, although it's unclear what his future may hold heading into the 2024 season.