The Flyers are being chased by five teams -- they lead Buffalo by four points -- and could ill-afford the third-period collapse against Toronto.
"We just played with way too much panic in our game," Philadelphia coach John Stevens said. "You have to have the courage to play. You have to have the courage to take people on 1-on-1. You have to have the courage to play a hockey game. To go out there and play panicky like we did tonight, throwing the puck away and not moving our feet, it was ridiculous."
The Maple Leafs outshot the Flyers 13-4 in the first period but were down 1-0. Upshall opened the scoring at 13:26 after getting behind Leafs defenseman Anton Stralman and taking a nice cross-ice pass from Vaclav Prospal. It was the seventh straight game the Maple Leafs allowed the first goal.
Coburn floated a point shot over a screened Toskala with 54.8 seconds to play in the second period while on a power play to give the Flyers a 2-0 lead. Toskala finished with 22 saves.
Briere made it 3-0 just 1:12 into the final period.
That gave Philadelphia a 2-0 lead at the second intermission and signaled bad things for the home team -- the Flyers entered the game with a record of 25-1-1 when leading after 40 minutes.
Despite that, they couldn't keep Toronto from rallying.
"They kept putting pressure on us, kept taking chances, and it paid off for them at a key time in the game," Biron said. "That pressure made it hard for us to do a lot of the little things."
Sundin has 16 points in his past nine games ... Antero Niittymaki made 54 saves in goal for the Flyers during a win in Toronto on Jan. 5.
Copyright by STATS LLC and The Associated Press
Arena: Air Canada Centre Location: Toronto, Ontario
Referees: Stephane Auger, Brad Watson Linesmen: Tim Nowak, Anthony Sericolo