O'Sullivan will make at least one more start Sunday, when he faces the Astros, the Providence Journal reports.
O'Sullivan effectively replaced Henry Owens in the rotation when Owens proved incapable of consistently commanding his pitches. In his first start, O'Sullivan didn't walk a batter, but allowed a whopping 12 hits in six innings. The high volume of hits may be explained away by O'Sullivan pitching to contact after Boston presented him with an 11-run lead. At any rate, he'll get at least one more start while the Red Sox have Eduardo Rodriguez (knee) toe the rubber for a fourth rehab start at Triple-A Pawtucket on Friday.