Jeff Carter scored an empty-netter in the final seconds to help the Flyers become the first team this series to win a game by more than one goal. The Flyers, trying to win their first title since 1975, nearly let the win slip away in the third.
Leading 4-1 early in the period, Chicago's Dave Bolland and Brian Campbell scored late goals to slice the deficit to one.
The home team has won all four games this series -- a factor that certainly favors the Blackhawks in Game 5.
Ville Leino also scored for the Flyers.
Game 5 is Sunday night in Chicago.
Hawks fans remain hopeful
Blackhawks fans hope that the home ice advantage is going to be good luck when the team returns to the United Center on Sunday. They are ready for the 'hawks to get back to friendly territory.
The fans streamed in hours ahead of the game. Flyers fans were less belligerent and 'hawks supporters were more numerous than Wednesday. They included Blackhawk Adam Burish' family.
"I can't watch sometimes. I just have to put my hands over my eyes and hope he doesn't get too hard. It's hard to watch as a parent," said Helen Burish, Adam's mother.
One Chicagoan scored a ticket for face value - $270 - at the last minute Friday.
"It's priceless. Priceless to see my first Stanley Cup game," said Howard Buckner, Blackhawks fan.
Two brothers from Edmington, Canada at the game grew up idealizing these two teams.
"We are here tonight and we're going to be in Chicago for Game 5," said Nick Boncuorem Blackhawks fan.
Inside before the puck dropped, the Philly bloodlust likely rivaled anything they saw in ancient Rome.
"It's intimidating around all this orange, you know what though, I am a fan, so go 'hawks!" said Lindsay Malhorn.
Chicagoans cheer for Hawks at home
Hawks fans crowded around TVs all over the Chicago area Friday night.
The mood among fans in Chicago was somber. But the 'hawks have their all-time great fans right behind them.
Bobby Hull, one of the men most responsible for the hawks' last Stanley Cup 49 years ago, was at 115 Bourbon Street in Merrionette Park and he said it's time for another.
"I was a Blackhawk the last time in '61 when we won the cup and I think this team is good enough to win," said Hull
Fans lined up to meet the 'hawks legend and prepared to watch their current 'hawks heroes.
"I have been hoping for this all year long. It has been a great long ride," said Jordan Hooks, Blackhawks fan.
The hawks' success has been a bonus for restaurants and bars which are packed with screaming hawks fans. Many are new to the sport.
"I'm the band wagon jumper. With all the bad teams here in town, I said the 'hawks are doing well. I'm going to come out and check it out myself," said Jordan Hooks.
The 'hawks got off to a rough start in the game and fans had very little reason to cheer, but the faithful said they still have confidence.
"They are going to come home Sunday and will have all of us cheering them on," said Laura Noonan.
"Chicago needs a champion team. We're not doing so good in other sports," said Tony Hay.
The Associated Press contributed to this report.