Sandoval (biceps/elbow) threw a 30-pitch bullpen session Wednesday, Christopher Smith of MassLive.com reports.
Sandoval will next progress to a live batting practice session Saturday, which will be the first time he's faced hitters since experiencing a setback in the form of a biceps issue in late April. The left-hander initially went on the injured list before the season as he continued his recovery from internal brace surgery. Sandoval noted Wednesday that he has a timetable in mind for a return, but he declined to divulge what it is. He threw 5.1 rehab innings before the setback and will need to restart a rehab assignment once he's deemed game-ready.