Toronto Blue Jays relief pitcher David Phelps left Wednesday's game against the Oakland Athletics after experiencing discomfort in his right shoulder, according to manager Charlie Montoyo.
Phelps was called upon to protect a 7-3 Toronto lead in the bottom of the eighth inning, but appeared to remove himself from the game while loosening up between frames.
The 34-year-old veteran is expected to undergo imaging on Thursday.
Phelps has been a key cog in Montoyo's bullpen early in the season, pitching to a 0.87 ERA through his first 11 appearances.
Tyler Chatwood took over on the mound after Phelps' departure.
