President of baseball operations Chris Antonetti said the right-hander is expected to have a bullpen session Friday or Saturday when the Indians are in Detroit.
Bieber, the reigning American League Cy Young Award winner, said last week he still believes he will pitch again this season even though his rehabilitation has taken longer than expected. Bieber is 7-4 with a 3.28 ERA in 14 starts.
The Indians have said Bieber has a strain in his rotator cuff. His velocity had noticeably dropped over his last few starts before the team decided to give him a rest. Bieber was 8-1 in the shortened 2020 season and led the majors in wins, ERA (1.63) and strikeouts (122).
Right-hander Aaron Civale is scheduled to pitch a simulated game Friday at Class A Lake County. He was tied for the major league lead with 10 wins when he sprained his right middle finger June 22.
"Both are continuing to progress," Antonetti said. "Aaron's ahead of where Shane is at this point in his progression."
Rookie right-hander Nick Sandlin, who strained his shoulder Wednesday against the Oakland Athletics, was placed on the 10-day injured list. Antonetti said Sandlin would have an MRI on Thursday. Sandlin has become a reliable part of Cleveland's bullpen, going 1-1 with a 2.94 ERA in 34 appearances.
Outfielder Harold Ramirez wasn't in Thursday's lineup after injuring his right knee sliding into second base Wednesday.
First baseman Bobby Bradley could begin baseball activities in a few days. He strained his left knee sliding into home plate Friday and is on the injured list.