The 36-year-old right-hander was injured while throwing a pitch during the eighth inning of Saturday night's victory over the Washington Nationals. An MRI exam Monday found a tear of the ulnar collateral ligament.

Isringhausen, who missed part of last season with the St. Louis Cardinals following elbow surgery, will undergo Tommy John surgery to repair the current damage. He was 0-1 with a 2.29 ERA in nine appearances this year.

The Rays placed Isringhausen, who has 293 career saves, on the 60-day disabled list on Sunday.