The Athletics outrighted Bielak to Triple-A Las Vegas on Wednesday.
Bielak was designated for assignment by the A's on Sunday.
The Athletics selected Bielak's contract from Triple-A Las Vegas on Sunday.
Bielak cleared waivers and was outrighted to Triple-A Las Vegas by the Athletics on Wednesday.
The Athletics designated Bielak for assignment Saturday.
Bielak (1-0) picked up the win in an extra-innings victory over the Rockies on Thursday, allowing a hit and a walk over one-third of an inning. He struck out one.
The Athletics acquired Bielak from the Astros on Thursday in exchange for cash considerations, Matt Kawahara of the Houston Chronicle reports.
The Astros designated Bielak for assignment Saturday, Chandler Rome of The Athletic reports.
Houston optioned Bielak to Triple-A Sugar Land on Friday.
Houston recalled Bielak from Triple-A Sugar Land on Thursday, Matt Kawahara of the Houston Chronicle reports.