Arizona Diamondbacks closer Justin Martinez will undergo Tommy John surgery and miss the rest of the season, manager Torey Lovullo said Friday, according to 98.7 FM's John Gambadoro.

Martinez exited Monday's win against the Seattle Mariners with tightness in his pitching elbow after his velocity dropped in the ninth inning. He was later diagnosed with a sprained UCL.

The 23-year-old finishes the season with a 4.11 ERA with five saves and 22 strikeouts across 15 1/3 innings. Martinez signed a five-year, $18-million contract extension in March.

Veteran right-hander Shelby Miller earned the first save for the Diamondbacks in Martinez's absence.

Left-handed reliever A.J. Puk has also been sidelined with an elbow issue since April but has been cleared to start throwing from 120 feet. Puk remains without a timetable to return.