Castillo (9-3) allowed three runs on seven hits and three walks over six innings Monday, striking out 10 and earning the win over the Cubs.
Castillo yielded a third-inning homer to Kyle Schwarber and allowed a pair of runs in the fourth inning but the Reds managed to tally five unanswered runs to earn him the victory. It was his first start with double-digit strikeouts since he fanned 11 on May 10. He'll carry a 2.41 ERA into Saturday's home start against St. Louis.