Joffrey Lupul netted a rebound during a power play 6:06 into overtime in Game 7 to lift Philadelphia past Alex Ovechkin and Washington 3-2 on Tuesday night in their Eastern Conference first-round series.
The Flyers led the best-of-seven series 3-1 before allowing the Capitals to pull even.
"For some reason, we don't like to do it the easy way," Flyers defenseman Braydon Coburn said. "We like to grind it out and do it the hard way. But it's a great feeling to get this series won."
Lupul found space in front of the net to get a backhander past Cristobal Huet after Washington's goalie had deflected Kimmo Timonen's shot.
"You're on a power play, the puck goes to the net, you end up banging it in, and 20 guys are ramming you into the boards," Lupul said about the celebration after his first playoff goal. "I'm still catching my breath right now. I'm sure it'll sink in here in the next couple of hours."
There were 9 seconds left in the Flyers' man advantage after defenseman Tom Poti was sent off for tripping - the first penalty since the second period in a rough-and-tumble game that suited Philadelphia's style.
"To have the referee decide the series like that, with two teams battling like that, is tough to swallow. I definitely didn't think it was a penalty," Poti said.
He then made reference to Philadelphia's second goal, when a Capitals defenseman was knocked into Huet by an opponent, and said: "It's tough to beat the officials as well as the Flyers."
The Flyers avoided what would have been a monumental collapse and won a playoff series for the first time since before the lockout: In 2004, they reached the Eastern Conference finals.
Now Philadelphia, which had the worst record in franchise history last season and the fewest points in the NHL, will play the top-seeded Montreal Canadiens in the conference semifinals. Game 1 is Thursday at Montreal.
Washington, meanwhile, dropped to 1-5 in Game 7s and is still waiting for its first playoff series victory since 1998, when it made it to the Stanley Cup finals. The Capitals will have to take solace in getting to the postseason for the first time since 2003, managing a remarkable turnaround under career minor league coach Bruce Boudreau, who took over for the fired Glen Hanlon on Thanksgiving with the team 6-14-1 and last in the 30-team NHL.
Led by Ovechkin, who topped the league with 65 goals and 112 points, Washington slowly climbed up the standings and won its last seven regular-season games - and 11 of its final 12 - to claim the Southeast Division championship.
"It's hard," Ovechkin said of the series loss, "but it's good experience for us."
He scored twice Monday night as Washington won at Philadelphia to force Game 7.
And Ovechkin had a hand in both of Washington's goals Tuesday, assisting on Nicklas Backstrom's opener 5:42 into the game, then scoring himself to make it 2-2 about 15 1/2 minutes into the second period.
Otherwise, Flyers goalie Martin Biron was brilliant, turning aside 39 shots. He came into the game with an 0-5 record when playing on the second of consecutive nights, a statistic coach John Stevens acknowledged was a concern before Game 7.
"I guess he answered those questions about back-to-back," Stevens said. "He was terrific. He had to be."
Biron was particularly good during the third period in which the Flyers were outshot 16-5. With about 6 minutes left in regulation, he preserved the tie by throwing his body backward to beat Alexander Semin to a rebound and smother the puck.
"Every time you get a shot, you hope you can make that save, that next save, to buy your team a little time to get some bounces or to get on the offense," Biron said. "In the third period, it was all about trying to buy some time."
Ovechkin made his presence felt from the outset. Just 1 1/2 minutes in, he delivered a big hit on Timonen along the boards behind net, separating the defenseman from his stick. Minutes later, Ovechkin slammed another defenseman, Braydon Coburn, into the glass.
After Philadelphia went ahead 2-1 on goals by Scottie Upshall and Sami Kapanen, Ovechkin gathered a pass from Brooks Laich near the blue line and - snap! - uncorked a shot that Biron didn't have time to even try to move into position to stop.
It was Ovechkin's fourth goal of his first NHL playoff series and prompted loud chants of "M-V-P!" from the red-clad, sellout crowd of 18,277. He celebrated by windmilling his left arm, sliding along one knee, then bouncing face-first off the glass.
By late in the game, though, Ovechkin appeared winded. When he had a chance on a breakaway in the third period, he sent a wild pass toward Sergei Fedorov that led to the Flyers heading the other way.
Kapanen's goal was effectively an empty-netter and surely will be a topic of discussion.
Right before a loose puck made its way to Kapanen, Philadelphia's Patrick Thoresen gave Shaone Morrisonn a shove, and the Washington defenseman plowed into Huet, knocking the goalie off his skates. The NHL posted an explanation on the Web, saying Thoresen legally body checked Morrisonn and no Philadelphia player made contact with Huet.
That reasoning apparently didn't make its way to the fans, who yelled insults and curse words at the on-ice officials.
Notes: This was the 30th Game 7 in NHL history to go to overtime. ... Players 24 or under scored 18 of Washington's 20 goals in the series. ... After missing the first six games of the series, Flyers RW Steve Downie made his playoff debut. ... Poti played despite getting hit in the head by another player's stick in Game 6.