Beckett, the ace of Boston's pitching staff, threw a 45-pitch bullpen session at the team minor league complex on Friday, according to reports.
The right-hander, who was scratched from a scheduled start on March 8 with back spasms, said he's beginning to making progress after a halting start to his rehab plan.
"There are still some peaks and valleys," Beckett said, according to The Providence Journal. "That first week I felt better every other day, and then every other day I felt worse. Now I'm at a point where I can do everything I need to do in between starts or bullpens. I've progressed, but it's only been in the last week where I can start to put a timetable when I can get on the mound."
Beckett started 30 games last year, going 20-7 with a 3.27 ERA. In the opener of the Red Sox's sweep of the Rockies in the World Series, he allowed one run and six hits in seven innings of Boston's 13-1 victory. He likely would have
started in Boston's season opener April 25 agaisnt the Oakland Athletics in Tokyo had he been healthy.
Instead, Beckett is slated to pitch in a minor-league game on Sunday. Rich Sauveur, the team's triple-A pitching coach, and head minor league trainer Jim Young will watch his progress.
Right-hander Bartolo Colon also stayed behind at Boston's minor-league complex and was scheduled to pitch in a game Saturday.