Spiers (shoulder) will begin a rehab assignment July 3 with the Reds' affiliate in the Arizona Complex League, MLB.com reports.
Spiers will be limited to three innings in his first outing for the ACL Reds. The right-hander has been on the injured list -- first the 15-day before shifting to the 60-day IL -- since April 20 with what was described as a shoulder impingement. Given the need for Spiers to build up innings and pitch counts, he's looking at multiple rehab starts before activation.