Williams (elbow) will throw a bullpen session Saturday, Adam McCalvy of MLB.com reports.
Williams has been able to throw off flat ground since early in the week, but he's now close to resuming mound work as he continues to make good progress in his recovery. The right-hander has been sidelined due to elbow discomfort since July 17, and it's not yet clear when he'll be able to return to game action.