Pittsburgh Penguins goalie Marc-Andre Fleury keeps his eye on the puck during second period Philadelphia Flyers-Pittsburgh Penguins NHL playoff play at the Wachovia Center in Philadelphia May 15, 2008. Philadelphia defeated Pittsburgh 4-2. (UPI Photo/John Anderson)

The Penguins lead the Eastern Conference Finals 3-1 and will try to earn a spot in the Stanley Cup Finals at home Saturday in Game 5.

Philadelphia scored more goals in the first period Thursday than it had in any of the first three games of the series.

Lupul scored on a slapshot 8:27 into the game and the Flyers then got power-play goals from Daniel Briere and Jeff Carter to take a 3-0 lead after one.

Pittsburgh got two goals from Jordan Staal in the third period, the second coming with 5:49 remaining in regulation, but Martin Biron was perfect the rest of the way and Lupul clinched it by scoring into an empty net with 32 seconds to play.

Biron made 36 saves and Pittsburgh's Marc-Andre Fleury had 30.

The loss was only the second for the Penguins in this year's playoffs. The Penguins swept the Ottawa Senators in the opening round and defeated the New York Rangers in five games in the conference semifinals.