Ray Emery will start for the Flyers in net in Tuesday's Game 3 of the Eastern Conference quarterfinals against the New York Rangers.
Emery and Mason shared time at practice Monday, but Mason announced afterward that he won't be ready by Tuesday.
Mason, who is targeting Friday for a return in Game 4, said he felt better Monday but didn't feel he was where he needed to be (see story). The Flyers' starting goaltender has not played since April 12 against the Penguins with whiplash (officially an upper-body injury).
Emery started the first two games for the Flyers and stopped 31 of 33 shots in Sunday's 4-2 win to even the series.