Jay Bouwmeester scored the game-winning goal as the Panthers defeated the Thrashers 3-2 on Saturday night.
It was the first victory for Florida over Atlanta in seven games this season.
The loss snapped a five-game win streak for the Thrashers.
"It was our best game against these guys this year," Florida coach Jacques Martin said. "We can enjoy it tonight, relax tomorrow and regroup for a similar challenge against Carolina on Tuesday."
With the teams skating 4-on-4, the Panthers stretched their lead to 3-1 on Bouwmeester's goal at 3:52 of the third period. His shot from just inside the blue line went through Lehtonen's legs.
"It was just one you put on the net," Bouwmeester said. "I was lucky it went in."
Tkachuk closed the gap to 3-2 at 15:29 of the third. Belfour blocked a shot by Hossa but the puck stayed in the crease. Tkachuk poked it past Belfour on the glove side.
The Thrashers were on a 6-on-4 power play after they pulled Lehtonen during the final 1:22 but couldn't take advantage.
"It was tough being in the [penalty] box seeing what is happening," said Jokinen, who was called for hooking. "It was good to get the two points. It's been a while since we beat that team. I was pretty confident we could pull it out."
The Thrashers took only two shots during the final power play.
"It was definitely a huge win," Belfour said. "The guys played hard right from the get-go and really deserved it. We've been working hard focusing on (penalty killing.) They did a great job."
The Panthers scored two goals in just over two minutes to take a 2-1 lead in the second period. Jokinen's shot from the right circle found the net when the puck went through a narrow space between Lehtonen's glove and the post to tie it at 1 at 5:48.
Horton gave the Panthers a 2-1 lead after his shot from above the right circle went over Lehtonen's left leg and into the net at 7:38.
"It was kind of a weird game," Lehtonen said. "I thought I made some great saves, but I let a couple of easy ones go in. That's what I'm not happy about."
Atlanta took a 1-0 lead at 9:28 of the first. Alexei Zhitnik took a shot from the left circle. Belfour stopped it but Hossa grabbed the rebound and beat Belfour glove side. It was Hossa's team-leading 40th goal. Hossa extended his point streak (seven goals, 10 assists) to 10 games, a new Thrashers team record.
"It feels good but it's a personal stat that doesn't mean anything if the team doesn't win," Hossa said. "We didn't deserve to win tonight. They were much better than us."
Hossa reached the 40-goal mark for the second time in his nine-year NHL career. ... Hossa has seven goals and three assists in seven games against Florida this season...Belfour started his 20th consecutive game for Florida.