Blach will replace Madison Bumgarner (ribs, shoulder) in the Giants' rotation, Alex Pavlovic of NBC Sports Bay Area reports.
Pitching coach Dave Righetti confirmed that Blach will get the first shot at replacing Bumgarner, who was injured in a recent dirt bike accident. Blach will be available out of the bullpen in an emergency Friday night, but he is expected to slot into the rotation Tuesday against the Dodgers. The lefty has three walks to just one strikeout in 4.2 innings so far this season.