Williamson will be called up from Triple-A Louisville to start Tuesday's game against the Rockies, Charlie Goldsmith of The Cincinnati Enquirer reports.
Williamson had already joined the Reds' taxi squad ahead of Monday's series opener in Coors Field, and as expected, he'll be thrust into the rotation for what will be a traditional start in his MLB debut. Even in a more pitcher-friendly venue than Coors Field, Williamson would be difficult to recommend as a streaming option, given that he hasn't looked especially sharp in the minors this season. Over eight starts in the International league, Williamson posted a 6.62 ERA and 1.88 WHIP with a 27:20 K:BB across 34 frames.