Underwood will start Game 1 of Wednesday's doubleheader against the Mets, Chris Halicke of DKPittsburghSports.com reports.
Underwood hasn't made a start since he covered four frames in his big-league debut in 2018, but he'll open Game 1 of Wednesday's twin bill. The right-hander has recorded more than six outs only twice this season and is unlikely to pitch deeper than an inning or two before giving way to the bullpen.