Buchholz threw 15 pitches in the bullpen and 15 more "short box," where the catcher sets up in front of the plate.
"He felt good, so that's really good news," said manager Terry Francona, who noted that the righty is scheduled to throw a bullpen session on Saturday. "Everything has been terrific, actually. If there's a point where we need to slow him down, we will."
The Red Sox have yet to rule out a return for Buchholz this year.
"We haven't closed the door on the fact that he might be able to pitch, which is certainly important," said Francona. "The other thing is that we want him to go home feeling good about himself, because this kid is an important part of not only our present, but our future."
Saturday's bullpen session could be telling of where Buchholz stands, particularly if his back feels good Sunday.
Jason Mastrodonato is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.