Buehler (ribs) threw off flat ground Saturday, but his scheduled bullpen session was pushed back to Sunday, Ken Gurnick of MLB.com reports.
Buehler was apparently still feeling pain in his ribs, which isn't a great sign, though if the session only ends up being postponed by one day it won't change his overall return timeline by much. The young righty hasn't pitched since June 8 after being shut down with a rib microfracture.