Phillies manager Rob Thomson said that Marsh is absent from Monday's lineup against the Mets due to illness, Matt Gelb of The Athletic reports.
Marsh is with the team, but it's unclear whether he'll be available off the bench. The Mets are scheduled to start southpaw Sean Manaea on Tuesday, so the left-handed-hitting Marsh could be held out of the lineup until Wednesday. Max Kepler, Harrison Bader and Nick Castellanos will serve as the Phillies' starters in the outfield Monday.