Henderson (back) was sent to Triple-A Nashville to begin a minor-league rehab assignment Sunday, Adam McCalvy of MLB.com reports.
Henderson will return to the mound in a contest for the first time since suffering a lower-back strain in late May. The right-hander has posted a 2.74 ERA and 1.04 WHIP with 30 strikeouts over 23 innings across five starts with the Brewers so far this season, and he has a strong chance of securing a spot in the major-league rotation once healthy.