Garver was scratched from Saturday's lineup against the Padres due to lower-back tightness, Ryan Divish of The Seattle Times reports.
Jhonny Pereda ended up starting behind home plate Saturday, and it's unclear whether Garver will be available for Sunday's series finale. Cal Raleigh (oblique) landed on the 10-day injured list Thursday, so Pereda would be the Mariners' top catcher if Garver were to also miss extended time.