There's something about games between the Flyers and Pittsburgh Penguins that makes it look as if both teams have beer-league defenses.

It happened in last year's wild playoffs, and it happened in last month's 11-goal game in Pittsburgh.

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It happened again Thursday night as the Flyers scored four first-period goals - two on the power play by the blistering Jake Voracek - but watched the Penguins answer with three unanswered tallies in the second period.

By the time it ended, both starting goalies had been yanked, and the Penguins emerged with a 5-4 comeback victory before a stunned sellout crowd at the Wells Fargo Center.

Eighteen seconds into the third period, Chris Kunitz, on a two-on-one, easily beat Brian Boucher to give Pittsburgh a 5-4 lead. A turnover by Kimmo Timonen set up the goal.

The Flyers lost a three-goal lead and lost in regulation for the first time since 1993, according to the Elias Sports Bureau.

The Penguins overcame an early 4-1 deficit as they won their third straight and sent the Flyers (11-13-1) two games under .500.

"We need to put a whole game together," said winger Zac Rinaldo, who had a goal and an assist in the first period. "We got the start we wanted, and then we got too comfortable with our lead."

Many of the Flyers seemed miffed that they couldn't give a solid 60-minute effort against their fiercest rivals.

"After the first period, we talked about [how] the Pittsburgh Penguins aren't going to sit back and just hand over two points," winger Scott Hartnell said. "They're going to come out hard, and, lo and behold, before you know it, it's 4-4. We just can't do that. It's embarrassing to the fans, it's embarrassing to one another, and we let another two points slip away."

Hartnell called the second period a "big letdown. I don't know why we would have stopped playing the way we were. . . .

"If we play like that, it'll be a long summer. We have to figure it out fast."

Kunitz had two goals, and Sidney Crosby had three assists to pace the Penguins (16-8), who are 10-4 on the road.

With 12 minutes, 53 seconds remaining, the Flyers thought they tied it at 5 when Hartnell tipped in Timonen's shot, but the goal was waved off. The war room reviewed it and said it was knocked in with a high stick.

Voracek, who had his first career hat trick in a 6-5 win over Pittsburgh last month, has nine goals and 19 points in his last 10 games.

The Flyers and Penguins combined for a ridiculous 56 goals in last year's six-game playoff series, and the teams had combined to average eight goals per game in their last 15 meetings before Thursday.

The Flyers outshot the Penguins in the opening period, 18-4, but Pittsburgh dominated the second.

Pittsburgh got goals that were credited to Pascal Dupuis and James Neal (Neal's pass deflected off defenseman Braydon Coburn's right skate and into the net) within 2:43 of each other, cutting the deficit to 4-3.

That caused Flyers coach Peter Laviolette to call a timeout with 11:47 to go in the second stanza. It didn't help.

The Penguins tied it with 4:13 left in the second period as Tyler Kennedy's drive went past Ilya Bryzgalov, who was screened by Brandon Sutter. Laviolette replaced Bryzgalov with Boucher, saying he wanted to change the momentum.

"We couldn't seem to get it back," he said.

Both of Voracek's first-period goals deflected off Penguins defenseman Paul Martin and through Fleury's legs. Hey, when you're hot, you're hot.

Fleury, who allowed an awful goal on a long shot by Timonen (three points), was pulled after the first period and replaced by Tomas Vokoun.

Vokoun had little work in the second period as the Penguins outshot the Flyers, 12-3. The Flyers had 18 shots in the first 20 minutes, then had just four shots over the next 27 minutes.

Breakaways. Winger Matt Read (ribs) returned to the lineup a month ahead of schedule and played on a line with Sean Couturier and Simon Gagne. Defenseman Nick Grossmann, injured in the first period against the Rangers on Tuesday, also returned to the Flyers' lineup.

Contact Sam Carchidi at scarchidi@phillynews.com. Follow on Twitter @BroadStBull.