Juan signed a minor-league contract Tuesday with Atlanta.
High-A Lansing activated Juan (elbow) from the 7-day injured list Thursday.
Juan (elbow) began a rehab assignment in the rookie-level Arizona Complex League on July 22 and has struck out eight over four scoreless innings between his first two outings with the affiliate.
Juan signed a minor-league contract with the Athletics on Monday.
The Athletics released Juan (undisclosed) on Sunday.
The Athletics designated Juan for assignment Sunday, Matt Kawahara of the San Francisco Chronicle reports.
Juan was held back in extended spring training for an unspecified reason, Jonathan Mayo of MLB.com reports.