The Oakland Athletics have placed left-hander Drew Pomeranz on the 15-day disabled list with a shoulder injury.
Pomeranz, who started Monday against the Houston Astros, left the game with one out in the fifth inning after experiencing tightness in the shoulder.
The 26-year-old is 2-3 with a 4.40 ERA this season.
The Athletics recalled right-hander Arnold Leon ahead of Wednesday's matinee at Houston.