Wacha (oblique) will throw a bullpen session Saturday as he works his way back from a recent setback, Jenifer Langosch of MLB.com reports.
Wacha had his rehab start Tuesday cut short and now may face a difficult time building back up to a starter's workload before the end of the season. It's unclear whether that will force the Cardinals to move him into a relief role for the stretch run. He new timetable should become clearer once the Cardinals see how he responds to his bullpen session.