The right-hander had a 2-1 count on Toronto's Troy Glaus and appeared to shake his pitching hand after the third ball crossed home. He signaled to the dugout, which brought out head trainer Ron Porterfield and manager Joe Maddon, as well as pitching coach Jim Hickey, and eventually went to the dugout without throwing another pitch.
The injury was later diagnosed as right shoulder tightness, and the Rays said they don't believe it to be serious.
Hammel was replaced on the mound by Juan Salas, who walked Glaus, though the walk was charged to Hammel.
At the time of his exit, Hammel was working from a 2-1 deficit and had thrown 54 pitches. The Jays scored twice on Hammel, using three hits and two walks. He also recorded a strikeout.
Dawn Klemish is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.