The Red Sox were optimistic that the injury that Buchholz suffered in San Francisco on June 26 would not require a trip to the disabled list, but the 25-year-old Texan was placed on the 15-day DL on July 5.
The team also announced that Manny Delcarmen will pitch for the Double-A Portland Sea Dogs on Thursday night, as he recovers from a forearm strain, and Josh Beckett will make his second rehab start for the PawSox on Saturday.
Beckett pitched four innings on Sunday, giving up one earned run on two hits, no walks and four strikeouts. He was placed on the DL on May 19 with back stiffness after he went 1-1 with a 7.29 ERA in eight starts to begin the season.
The team will hold a voluntary workout on Wednesday evening at Fenway Park, presumably without its six All-Stars.
The disabled list remains crowded, with Dustin Pedroia (foot), Victor Martinez (thumb) and Jason Varitek (foot) out for at least a few more weeks. The statuses of Jacoby Ellsbury (ribs), Jeremy Hermida (ribs) and Mike Lowell (hip) could be updated when Terry Francona addresses the media on Wednesday.