The Athletics optioned O'Loughlin to Triple-A Las Vegas on Sunday.

The 24-year-old southpaw received his first big-league call-up May 25 and tossed seven shutout innings over his three appearances out of the Oakland bullpen. After covering 3.1 frames in relief in Saturday's 7-0 loss to the Blue Jays, O'Loughlin wasn't expected to be available for at least the next couple of the days, so Oakland will swap him out of its bullpen for right-hander Michel Otanez, whose contract was selected from Las Vegas in a corresponding move.