Bieber (shoulder) will throw a side session off a mound Tuesday, Keegan Matheson of MLB.com reports.
Bieber hasn't pitched since Aug. 20 due to shoulder inflammation, and he'll have to build his arm back up before returning to game action. The right-hander will be up against the clock to make it back in time before the end of the regular season. He underwent an MRI on Sunday to confirm that the injury was healing, and the team was encouraged by the results of his imaging, per Hazel Mae of Sportsnet. Bieber has made just 11 starts this season, posting a 4.37 ERA, 1.42 WHIP and 44:24 K:BB across 55.2 innings.