WASHINGTON - A sense of doom that apparently is bred into so many of Philadelphia's sports fans prevailed Monday night as the Flyers dejectedly skated off the ice and the Wachovia Center emptied.

The Flyers had let a three-games-to-one lead in their first-round series against Washington evaporate and had to drag their weary and sore muscles back down to the nation's capital for the deciding Game 7 tonight. They had no momentum and no playoff history with this group.

After the Game 6 loss, coach John Stevens said the Flyers would learn what they were made of, his blunt way of issuing a challenge to his players.

In a game in which every inch of ice was contested, Joffrey Lupul poked in a rebound on a power play at 6 minutes, 6 seconds of overtime to give the Flyers a 3-2 win over the Caps. They advanced to the second round of the Stanley Cup playoffs for the first time since 2004.

They will play the Montreal Canadiens in Round 2.

It seemed appropriate in this closely played series that the teams went into the third period locked in a 2-2 tie and that each had come from behind after being down a goal.

In the second period, goals came from the most likely and one of the least likely players.

Sami Kapanen, whose talent lies in his checking and penalty killing, gave the Flyers a 2-1 lead midway through the second on a goal he would have been embarrassed not to get. Kapanen shot into an open net after goalie Cristobal Huet was wiped out in a collision with teammate Shaone Morrisonn. The red-clad crowd screamed foul, believing the Flyers' Patrick Thoresen drove Morrisonn into the goalie.

But Alexander Ovechkin changed the fans' mood by whistling a wrist shot from high in the face-off circle through goalie Marty Biron to tie it at 2-2.

In a game played at a remarkably quick pace, the Flyers came out for the opening period and brought their hearts but not their heads as Scott Hartnell and Derian Hatcher got caught for needless penalties.

After Hatcher went to the box for trying to rearrange the face of Brooks Laich along the boards, the Caps had a two-man advantage, and Nicklas Backstrom cashed in to give Washington a 1-0 lead just 5:42 into the game.

Backstrom's goal was reminiscent of the one scored by Mike Richards in Game 6. Ovechkin ripped a shot that caromed off the board behind the Flyers' net and went right to Backstrom. Biron never had a chance.

The Caps spent the next several minutes dominating possession, buzzing around Biron for long stretches. A hooking penalty against Alexander Semin broke Washington's momentum and also led to the tying goal by Scottie Upshall, whose shot from the point trickled through the pads of Huet, who was screened by the Flyers' R.J. Umberger.

Moments later, Upshall was having a cut on his chin attended to and didn't mind because it was the result of a high stick by Sergei Fedorov, who drew a double minor. Then David Steckel exacerbated the Caps' problem by getting a hooking penalty 18 seconds later.

So the Flyers had a two-man advantage for 1:42 and the rest of the period on the power play, a golden chance to take the lead into the second period. Huet held firm, fighting off shots by Danny Briere, Vinny Prospal and Braydon Coburn. He also caught a break when Joffrey Lupul missed an open net from the corner of the crease.

This series, the 13th in Flyers history to extend to seven games, began to turn in Washington's favor after coach Bruce Boudreau flip-flopped his first- and second-line centers before Game 4. The moved balanced the Caps' attack and gave the Flyers another line to concern them.

Boudreau moved the savvy and creative veteran Fedorov up to center Ovechkin and Viktor Kozlov, forming an all-Russian line. He dropped the rookie Backstrom to the second line with Semin. The move seemed to awaken both Backstrom and Semin, who had combined for six goals and 10 points in the previous three games. Much of their success had come against the Flyers' line with Briere and Prospal, both of whom were defensive liabilities in Game 6.

Stevens gave rookie Steve Downie his first sampling of playoff action. Downie had been a healthy scratch in 11 of the Flyers' final 17 games. He has yet to earn the trust of Stevens at the defensive end of the ice, but Downie has some offensive skill, and obviously the coach thought he was a better option than Riley Cote.

The Flyers were trying to avoid squandering a three-games-to-one lead for the third time in their history. They did so in 1988 against Washington in the first round on Dale Hunter's overtime goal and in 2000 against New Jersey in the Eastern Conference finals. That seventh game will be remembered for Scott Stevens' open-ice hit on Eric Lindros, which left him with a concussion.

The Caps have not won a playoff series since 1998 and have not been to playoffs since 2003.

Since the NHL went to the best-of-seven format in 1939, the home team had won 77 of 121 for 64 percent.

Tonight was only the eighth time in history that Games 6 and 7 were played on consecutive nights and only the fourth time since 1950. The Flyers were 6-6 in seventh games.

Contact staff writer Ray Parrillo at 215-854-2743 or rparrillo@phillynews.com.