Mariners reliever David Phelps has a torn UCL in his pitching elbow and will have season-ending Tommy John surgery, the team said Thursday.
The right-hander is expected to be sidelined 12-15 months.
Phelps was expected to serve in a setup role this season for Seattle, which acquired him from the Marlins last July.
He suffered the injury on the final pitch of his last spring appearance, Saturday against the Angels.