McCullers (forearm) will report to Triple-A Sugar Land to make a rehab start Tuesday, Chandler Rome of the Houston Chronicle reports.
The right-hander started his rehab assignment Friday with Double-A Corpus Christi, and he threw 40 pitches over two frames in that outing. McCullers will continue to build up his workload Tuesday, and he'll likely require at least two additional rehab starts following that appearance before being cleared for his season debut with the Astros.