O'Sullivan will start Friday's game against the Rays, Brian MacPherson of the Providence Journal reports.
It came down to O'Sullivan or Clay Buchholz, and O'Sullivan earned a second start after he carried a shutout into the sixth inning of Sunday's win over the Angels. An additional factor was that manager John Farrell liked the idea of having Buchholz available out of the bullpen a day earlier than O'Sullivan would be available. We're taking this one day at a time with O'Sullivan as the fourth starter, but presuming he pitches well Friday, he'll remain in the rotation following the All-Star break.