Lupul scored two goals, Martin Biron made 31 saves and Philadelphia beat Nashville 4-1 on Saturday night to snap the Predators' winning streak at six games.
Mike Richards and Claude Giroux also scored to help the Flyers bounce back from a 5-1 home loss to Calgary on Thursday night.
"We really focused on the start of the game because that's what did us in against Calgary," Lupul said, referring to the Flames' four-goal first period. "Even though it was 0-0 tonight, we had some confidence going into the second. Our penalty kill did a good job and we got some timely goals."
Lupul has 20 goals this season.
"He's a big strong guy who gets to the net very well and has a knack for scoring," Richards said. "The last couple of weeks, even all year, he's been playing really well for us."
Martin Erat scored for the Predators, who missed a chance for the second-longest winning streak in franchise history. The Predators opened the 2005-06 season with eight straight wins.
"We didn't get our game started today," said Kevin Klein. "We got away from what has led to our success -- playing physical, chipping pucks in, and really forechecking them hard. They punished us on special teams especially."
Biron made spectacular glove saves on Erat while sprawled on his back midway through the first period, and on Ryan Jones and Jason Arnott on second-period power plays.
"There's no magic recipe," Biron said. "We're a good team and when we don't complicate things we usually play good. Give credit to Calgary. The other night they put pressure on us right away. We were never able to get our legs or our momentum going. Tonight we did."
Richards put the Flyers ahead on a power play 45 seconds into the second period with a one-timer from the right circle that glanced off and then slid under goalie Pekka Rinne's pad.
Nashville had killed off 19 straight power plays over the past seven-plus games before Richards' goal.
Lupul made it 2-0 at 4:22 of the period when he took a cross-ice pass from Kimmo Tomonen and poked the puck off Rinne's blocker into the net.
"No excuses," said Rinne, who had won six straight games and posted an 11-2-1 record since Jan 30. "We played really well for about 50 minutes or so but we pretty much gave it away on those two goals."
Erat scored on a wrist shot from the slot at 7:45 of the third period, but Lupul put the Flyers ahead 3-1 just 1:06 later when he rebounded Daniel Carcillo's backhanded attempt into the goal.
It was the first Flyers' point for Carcillo, who was obtained from Phoenix in a trade for Scottie Upshall last Wednesday.
Carcillo, who went into the game leading the NHL with 174 penalty minutes, was called for his first infractions with the Flyers, a minor for unsportsmanlike conduct, and a major for fighting with Greg de Vries.
Giroux took advantage of a Nashville turnover to score from slot with 3:13 left.
Philadelphia C Daniel Briere was out after reinjuring his groin against Calgary on Thursday. ... The Predators had outscored their opponents 28-11 during their winning streak.