Heisey hurt his groin while legging out a triple in Saturday's game, Dan Kolko of MASN Sports reports.
He went 1-for-4 with a run and a walk, but that one hit was costly, as it sounds like he will be unavailable for Sunday's series finale against the Diamondbacks. Ryan Raburn is going on the bereavement list Sunday and Jayson Werth and Michael Taylor are already on the DL, so the Nationals' outfield will be stretched incredibly thin in the short term.