Williamson (shoulder) allowed one run on two walks while striking out three over two innings for Double-A Chattanooga on Saturday. The left-hander also hit a batter.
Williamson, who was shut down in April with shoulder fatigue, kicked off a rehab assignment with the Lookouts. After first-inning control issues -- a hit by pitch and a walk -- Williamson settled in before rains came and prompted an early exit after 39 pitches (22 strikes).