Halpern had a goal and two assists and the Tampa Bay Lightning beat Florida 3-1 on Tuesday night.
Florida, 8-1-1 in its last 10 games, fell five points behind Boston for eighth place in the Eastern Conference. They are three points behind ninth-place Washington, tied with Buffalo for 10th.
But then the Panthers, who have not made the playoffs since 2000, might have been their own worst enemy.
"Some people weren't good enough," Panthers coach Jacques Martin said. "That's the bottom line. We had one line. [Center] Stephen Weiss' line produced nine scoring chances for us. Other people have to pull their weight."
A mistake by Boyle helped the Panthers tie the game in the second. Boyle, looking to clear the puck from the Tampa Bay zone, whiffed and the puck was stolen by David Booth, who scored on a wrist shot past Karri Ramo.
Halpern, who had played just 13 seconds in the past two games due to an abdominal strain, gave Tampa a 2-1 lead 1:11 into the final period with his 17th goal of the season.
Lightning defenseman Filip Kuba added an empty-net goal with 51.2 seconds left in the game.
"For whatever reason, for such a big game, we didn't come out like we needed to," Panthers defenseman Bryan Allen said. "And [we] didn't have that jump and that desperation. It's amazing how the first five minutes can dictate the whole game."
The Lightning outshot Florida 11-7 in the first, but were outshot 16-4 in the second due to numerous turnovers.
"I was lost on the second goal they scored," Jokinen said. That probably cost us the hockey game. If there's somebody to blame, I take the blame."
Lightning coach John Tortorella had no qualms about putting a near devastating blow on the Panthers playoff chances.
"I'm not crazy about [their] organization," Tortorella said about hurting Florida's playoff chances. "I don't mind at all. Just fine with me."
Ramo, who got a rare start in place of Mike Smith, made 34 saves for the Lightning and picked up his sixth win in 19 games. Smith hurt his knee in practice on Monday.
The Panthers, who played back-to-back games against the Lightning, face Atlanta on Thursday, the team with the second-worst record in the Eastern Conference at 70 points.
Panthers LW Jozef Stumpel returned after missing the previous 23 games with a shoulder injury. ... Florida LW Ville Peltonen was out of the lineup with a broken toe he suffered in Saturday's 4-2 win against Tampa Bay.