Susac exited Thursday's contest against the Athletics in the sixth inning as a result of back tightness, Susan Slusser of the San Francisco Chronicle reports.
Susac was forced out of the game ahead of his at-bat in the bottom of the sixth inning, ultimately being replaced by Eric Haase behind the plate. Susac finished his day having gone 0-for-2 with a strikeout at the plate, and he is considered day-to-day ahead of Friday's series opener at home against Atlanta.