Wahl was diagnosed with a torn ACL in his right knee Sunday, Adam McCalvy of MLB.com reports.
Wahl suffered the injury Friday and is now likely done for the season. The 26-year-old -- who was acquired by the Brewers in a trade for Keon Broxton -- will still seek out a second opinion to confirm the diagnosis. Wahl figured to begin the season at Triple-A San Antonio but likely would have gotten a chance in Milwaukee's bullpen at some point.