The right-hander last pitched for the Red Sox on June 19 before being sidelined with a stomach illness that was diagnosed as esophagatis, which required a short stint in the hospital and a trip to the disabled list.
"Buchholz is pitching tomorrow, maybe a 40-pitch stint just to get his spikes on the rubber and not go 24 days in between being on the hill," said manager Bobby Valentine.
Buchholz is on track to return to Boston's rotation during a three-game series on the road vs. the Rays that begins on Friday.
"If that goes well tomorrow, then he'll be able to pitch in the first series coming out," Valentine said.
In his last five starts before going on the DL on June 24, Buchholz was 4-0 with a 2.43 ERA and 31 strikeouts in 37 innings. This season he's 8-2 with a 5.53 ERA in 14 outings.
In other injury news, Jacoby Ellsbury (right shoulder) was scheduled to play with Triple-A Pawtucket on Saturday. Ryan Sweeney (left big toe) was not scheduled to play Saturday. Righty Chris Carpenter (right elbow surgery) was set to pitch for Class A Greenville on Sunday.