Without any of their regular starters available thanks to the recent run of rainouts and doubleheaders, the Red Sox activated Richard Fitts from the injured list after just one rehab start and will have the right-hander start on Tuesday in Milwaukee.

To clear space on the active roster the Red Sox optioned right-hander Zack Kelly to Triple-A. The Red Sox also activated left-hander Zach Penrod (left elbow sprain) from the 60-day IL and optioned him to Triple-A.

Fitts was placed on the 15-day IL with a right pectoral strain on April 13 and missed 39 games. Prior to the injury Fitts posted a 3.18 ERA in 17 innings over his first three starts with Boston, and last Thursday he threw three scoreless innings in his lone rehab start with Double-A Portland.

Dating back to last September, Fitts has a 2.39 ERA in seven career MLB starts. He will face off against Milwaukee's Aaron Civale (0-1, 9.00).