Gutierrez came on to start the sixth inning and allowed a walk and a single before catcher Henry Blanco went to the mound.
"I was warming up and my shoulder didn't feel good," Gutierrez said. "But I was thinking once I get warm I'd be all right. Henry came to me and said, 'Hey, you look weird. You got something hurt?' I told him, 'Yeah, I don't feel good.' [He said] 'You've got to tell them you don't feel good.'"
Gutierrez, who has a 5.40 ERA, will return to Phoenix to be examined by team doctors, but initial indications are that he will have to be placed on the disabled list.
"When I played catch in the morning I felt it, but I thought it was all right because we had the day off yesterday," Gutierrez said. "Maybe a little tight. But I thought it was going to loosen up."