Castillo is scheduled to start Wednesday against the Brewers, Bobby Nightengale of The Cincinnati Enquirer reports.
Castillo was originally scheduled to take the ball Thursday against Pittsburgh, but the Reds wanted to steer the young right-hander away from a rematch with the Pirates after he faced them in his season debut. As such, the team decided to flip Castillo and Tyler Mahle in the rotation. In his first start this season, the 26-year-old Castillo allowed one run on two hits over 5.2 innings against the Pirates, striking out eight and walking three in a no-decision.