Williams is slated to start Saturday's game against the Diamondbacks in Arizona, Mike Puma of the New York Post reports.
Williams has covered a total of 1.2 innings between his two relief appearances on the season, but he'll be pressed into a starting role Saturday after a rainout earlier in the week required the Mets to break add an extra man to the rotation temporarily. According to Puma, manager Buck Showalter said Williams "would be more than an opener" Saturday, but fantasy managers should temper expectations for the right-hander's workload, given that he isn't fully built up for starting duty.