Doubront accompanied the team to Oakland and said he expected to pitch Friday. Manager John Farrell said after Wednesday's 2-1 victory over the Twins that Doubront was a strong candidate to start Friday, but the team didn't have an announcement yet.
Workman will next be eligible to pitch for the Red Sox on June 24.
The Red Sox will need to open up a roster spot by Friday, and third baseman Garin Cecchini, who was recalled Tuesday, will likely be optioned back to the Minors at that point.
Workman was disciplined for throwing a pitch behind Evan Longoria on May 30 at Fenway, and his appeal was heard by MLB on June 13.
Doubront is 2-4 with a 5.12 ERA in nine starts for the Red Sox this season. He was sidelined with a left shoulder strain.
Workman has done a stellar job since replacing Doubront, going 1-0 with a 3.21 ERA in five starts.
Clay Buchholz will also return to the rotation soon, creating some real competition.
Rubby De La Rosa has also been impressive of late while filling in.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.