Callahan has been promoted to Triple-A Pawtucket, Christopher Smith of MassLive.com reports.
Callahan made quick work of Double-A Portland, pitching just 13 innings before heading up to Pawtucket. The converted starter posted a 1.38 ERA with 20 strikeouts and no walks over 10 relief appearances. This year is ahead of schedule for the 22-year-old right-hander to reach Boston but clearly the Red Sox feel he's ready for the challenge of Triple-A.