McCullers (forearm) is scheduled to throw 25 warmup pitches Saturday and then sit down to mimic a break between innings before re-taking the mound, Chandler Rome of The Athletic reports.
Saturday's session will be McCullers' first up-down since undergoing surgery last June. He's expected to simulate one more up-down before the Astros consider having the right-hander face hitters. McCullers appears to be on track for an August return.