Philly held the Penguins to just 17 shots on goal, with only five in both the first and second periods, respectively. This marked the Flyers' first playoff win since 2020.
Teams that win the first game of their respective series in the first round go on to advance 68% of the time.
After a scoreless first, Jamie Drysdale put the Flyers up 1-0 halfway through the second with a wrister through the five-hole.
But Pittsburgh would respond five less than five minutes left in the period.
Long-time Penguin and future Hall of Famer Evgeni Malkin got Pittsburgh on the board, tying it up 1-1 before heading into the second intermission.
Heading into the third period, both teams were 0-for-3 with the Flyers outshooting the Pens 16-10 at that point.
Much like Drsydale in the second, teammate Travis Sanheim would score exactly at the halfway mark in the third to put Philly up 2-1.
Just seven minutes later, Porter Martone would make NHL history for the Flyers.
The 19-year-old would become the fifth-ever teenager to score an eventual game-winning goal in their Stanley Cup Playoffs debut.
Martone would rip a snipe off the post that put the Flyers up 3-1, which was just enough to seal the Game 1 win.
Pittsburgh wouldn't let up in the end, putting the pressure on the waning minutes of the third.
After Sanheim and Sidney Crosby both got called for two-minute minors as they went at each other with cross-checks and slashes, Pittsburgh's Bryan Rust would score on the power play with the empty net to make 3-2.
Flyers goaltender Dan Vladar, who hadn't seen much action in the night thanks to the Flyers' wonderful defense, would make a last-second save right in front of the net to seal the win.
Philly's Christian Dvorak put up the best player rating of the game with a 7.6.
Game 2 between the Flyers and Penguins will be on Monday, April 20th, at 7:00 p.m. Eastern time.