With the Flyers facing elimination, Boucher took over with the Sabres up 3-1 on Sunday and after Leighton allowed three goals on seven shots in the first period. Buffalo leads the best-of-seven series 3-2.
It marked the third time this series the Flyers have changed goalies during a game. Leighton got the start on Sunday, two days after replacing Boucher, who was yanked after allowing three goals on 11 shots in Buffalo's 4-3 overtime win.
Despite his struggles in Game 5, Boucher is 2-1 in the series, including a 28-save performance in a 1-0 loss in Game 4.