Williamson will start Tuesday's game in Atlanta.
After working out of the bullpen in each of his previous three appearances, Williamson will re-enter the rotation with the Reds placing Chase Burns (groin) on the 15-day injured list Sunday. Williamson had covered four-plus innings in two of those appearances while piggybacking Burns, so he should be sufficiently stretched out as he rejoins the rotation. Williamson could be in store for two starts this week, with another turn potentially coming in the season finale Sunday in Toronto.