Brebbia will serve as the Giants' opening pitcher in Sunday's game against the Cubs, Maria I. Guardado of MLB.com reports.
While opening Saturday's 4-0 loss, Brebbia tossed 19 pitches and worked two scoreless frames. He'll get another "start" Sunday, but he's unlikely to cover more than one or two innings before turning the game over to the bullpen. Tristan Beck is expected to work as the bulk hurler after Brebbia leaves the game, though Beck may not have an extended leash after covering 2.1 innings out of the bullpen Friday.