Barria is starting Game 1 of Saturday's doubleheader against the Mariners, Sam Blum of The Athletic reports.
He has gone between two and four innings in each of his last five appearances out of the bullpen, having most recently thrown two innings Wednesday, so this will essentially be a bullpen game. Barria has a 2.55 ERA, 0.96 WHIP and 38 strikeouts in 53 innings this season.