Toronto rallied from a 4-2 third-period deficit to earn its third consecutive preseason victory (3-1-0).
After a bruising first period that saw Toronto jump out to a 2-1 lead, the Flyers rallied with three unanswered goals in the middle frame while outshooting the Leafs 16-3.
With Philadelphia on a two-man advantage early in the second period, Pronger one-timed a point shot past Maple Leafs goalie Vesa Toskala at 6:53 to tie the game at 2-2. Then it was Briere's turn as the winger scored twice in the second period, at 8:41 and 16:58.
Toskala played the whole game -- his first full game of the preseason -- and stopped 25 shots.
Toronto was 2 for 10 on the power play, while Philadelphia went 2 for 7 with the man advantage.
Phil Kessel, who was obtained in a trade with Boston on Friday, was introduced to the Air Canada Centre on the scoreboard midway through the first period. "Toronto's a great team, the fans are outstanding, and it's going to be a great year," said Kessel as the crowd roared its approval. "The fans here are the best in the league." Kessel signed a $27-million, five-year deal with Toronto, but is out until November while recovering from offseason shoulder surgery.