Williams is no longer starting Wednesday against the Nationals after Mychal Givens (illness) was reinstated from the COVID-19 injured list to serve as the starter, Anthony DiComo of MLB.com reports.
The Mets haven't given any indication that Williams is unavailable Wednesday, so it seems likely that he'll be an option to serve as a bulk reliever behind Givens against Washington. Williams allowed at least one run in each of his six appearances in September, posting a 5.14 ERA and 1.57 WHIP in 14 innings over that stretch.