" Huston Street will undergo an MRI this morning on his right biceps, and said there's no timetable for his return. Franklin Morales will take over as the closer, manager Jim Tracy confirmed.

Street believes he's dealing with biceps tendinitis, so he's hoping to return in a few days.

"But right now, I just don't know. It's frustrating given how great this season has gone for the team and me, you want to be at your best when it matters most," said Street, who is not feeling pain in the upper part of the arm near his shoulder, which is a good sign.

"I don't believe it's serious, but I don't know yet."

Morales will take over as closer, leaving Rafael Betancourt in the setup role. Tracy is mindful that Betancourt has struggled in the ninth during his career and Morales profiles as a closer - a left-hander who throws 96 to 97 miles per hour."