Right-hander Chris Volstad will start in place of Garza, who the club is hopeful will be able to start Sunday's series finale.
"He's a little under the weather," Sveum said. "He's pretty down now."
Volstad will be pitching on regular rest because of Monday's postponement in Cincinnati. The 25-year-old right-hander is 3-3 with a 4.46 ERA in six career starts against the Dodgers.