The Detroit Tigers announced this morning that closer Joe Nathan underwent an MRI, which revealed a tear in his Ulnar Collateral Ligament in his throwing elbow. Doctors also discovered a tear in his flexor-pronator tendon in the same elbow.

Those two tears will force the 40-year-old hurler to go under the knife for season-ending surgery, which the Tigers reported would occur at a later date.

Nathan is seventh all-time in career saves with 377 and missed the entire 2010 season following Tommy John surgery. The 14-year veteran is in his second season with the Tigers after stints with San Francisco, Minnesota and Texas. He's been on the 15-day disabled list since April 9th and was expected to throw a simulated game in Toledo on Saturday.

Joakim Soria has stepped in to the closer role since and has five saves to his credit, allowing just two hits in eight appearances this season.