Abbott (shoulder) threw a bullpen session Tuesday, MLB.com reports.
The side session was Abbott's second since he landed on the 15-day injured list Aug. 23 with a left shoulder strain. Abbott is expected to face hitters in live batting practice this weekend, and if all goes well, he could return from the IL next week to make one final appearance before the end of the regular season. Given that he'll have missed more than a month and won't have the benefit of making a minor-league appearance beforehand if he's activated, Abbott is expected to be limited to a relief role.