Williamson will start the fifth game of the regular season, March 31, against Pittsburgh, Rich Rovito of MLB.com reports.
Williamson was planned to be part of a three-pitcher grouping that would occupy the fourth and fifth rotation spots, but that plan changed. The Reds need to adjust to being without Nick Lodolo (blister), who will open the regular season on in the injured list. That paves the way for Williamson, Chase Burns and Rhett Lowder to each have their own spot in the rotation to begin the season.