05/03/2012 08:04 EDT | Updated 07/03/2012 05:12 EDT

Yankees manager Joe Girardi says Mariano Rivera has torn knee ligament

KANSAS CITY, Mo. - New York Yankees manager Joe Girardi says closer Mariano Rivera has a torn right knee ligament, an injury that could potentially end his career.

The 42-year-old right-hander was carted off the field after twisting his right knee shagging flyballs during batting practice Thursday night before the Yankees played the Kansas City Royals.