Boston is carrying 13 pitchers overall, including eight relievers. After talk that the Red Sox would take a hitting prospect for the final, 25th spot, manager Bobby Valentine elected to keep an extra pitcher on hand after learning that closer Andrew Bailey is out for four to five months with a thumb injury.
Jon Lester will start on Opening Day, and Alfredo Aceves has been given the closer job.
With outfielder Carl Crawford still battling injuries, the three outfield positions will be taken care of by Jacoby Ellsbury, Darnell McDonald, Cody Ross and Ryan Sweeney.
Crawford (left wrist) has been placed on the 15-day disabled list, retroactive to March 26, as have pitchers Rich Hill (left elbow), Daisuke Matsuzaka (right elbow) and Andrew Miller (left hamstring). Bailey, pitcher Chris Carpenter (right elbow) and outfielder Ryan Kalish (left shoulder) are all on the 60-day disabled list.
Infielders Pedro Ciriaco and Nate Spears and outfielder Jason Repko will all go to Triple-A Pawtucket, while catcher Daniel Butler has been assigned to Double-A Portland.
The Red Sox face the Detroit Tigers at Comerica Park at 1:05 p.m. Thursday, with Justin Verlander and Lester the starting pitchers.