The Royals activated Lorenzen (hamstring) from the 15-day injured list Wednesday.
Lorenzen will rejoin the rotation Wednesday versus the Nationals after missing the last four weeks of action with a strained hamstring. The righty was limited to 1.2 and 3.2 innings in his two minor-league rehab appearances, so he'll likely be operating on a restricted workload in what will be his final start of the regular season.