Williamson (shoulder) is scheduled to make a rehab start for Triple-A Louisville on Tuesday, C. Trent Rosecrans of The Athletic reports.
Williamson, who threw two innings at the Reds' complex in Arizona last Thursday, is scheduled for three innings in what will be the first appearance of his second rehab assignment. The left-hander opened the season on the injured list due to a left shoulder strain and was pulled off an earlier rehab assignment in June, when he was diagnosed with a Bennett lesion in the shoulder.