Mooney suffered a hamstring injury during Sunday's game at Denver, Tori McElhaney of the Falcons' official site reports.
Mooney made a midweek appearance on the Falcons' Week 11 practice report with an Achilles issue but ultimately was cleared Friday. He now is dealing with a separate health concern, and if he's unable to return, he'll finish with two catches (on four targets) for 27 yards.