"We knew we were facing a desperate hockey team, but it was more about this dressing room to be honest with you," Denis said. "We needed to find our identity and get back to our brand of hockey."
Denis lost his bid for his first shutout of the season and 16th overall when Sami Kapanen scored a short-handed goal with 4:12 left.
"I think the most important thing that hopefully we can learn from this game as we move forward is, it's just about being accountable," Tampa Bay coach John Tortorella said. "Being accountable to yourself and your teammates."
The Lightning, who had lost four of five, also got third-period goals from Vinny Prospal and Nikita Alexeev. Tampa Bay has won nine straight games against the Flyers, outscoring Philadelphia 43-16.
"It's only good if we go in and do something good in Washington (Saturday)," said Tampa Bay center Brad Richards, who had two assists. "You've got to back these wins up."
Philadelphia center Peter Forsberg left in the first after spraining his left wrist. The Flyers' captain, who will miss Friday night's game at Florida, was hurt when he used his arm to brace himself against the boards. A team official said X-rays were negative.
"The hand got squeezed in the boards," Forsberg said. "I don't know exactly how it's going to take, but not too long. Hopefully, it's just a sprain and maybe a week or so."
Forsberg is scheduled to be re-examined by a specialist Friday in Orlando.
"We don't think it's broken," Philadelphia coach Ken Hitchcock said. "We'll have a better update in the next 24 hours."
Antero Niittymaki made 32 saves for the Flyers, who were coming off a 9-1 loss to Buffalo on Tuesday night. Philadelphia has dropped four in a row.
"We didn't capitalize on our chances," Hitchcock said. "There's a fine line between winning and losing right now."
Craig put the Lightning ahead 1-0 at 7:38 of the second when he made a waist-high deflection off a tipped pass from Richards. Criag left later in the second with a right knee injury and be re-examined Friday.
Fedotenko made it 2-0 on a rebound goal with 6:12 left in the second. Philadelphia has been outscored 15-6 during the second this season.
- The Flyers sent C Petr Nedved and LW Niko Dimitrakos to Philadelphia of the AHL. Both had been placed on waivers Wednesday.
- Craig has four goals in three career games against Philadelphia.
- Flyers D Mike Rathje returned after missing five games with a back injury.
- Lightning C Andreas Karlsson (strained groin) played after sitting out five game.