PHILADELPHIA -- The best team in the Southeast Division just can't beat the worst team in the NHL.
Geoff Sanderson had a goal and an assist, and Derian Hatcher scored for the first time in more than a year for the Flyers, the owners of the league's worst record (20-40-11).
"I looked at the sheet before the game and saw that the Flyers had won the first three meetings," said Martin Biron, who stopped 37 shots and is 4-2-1 since Philadelphia acquired him from Buffalo on Feb. 27.
"This (Atlanta) is a team that I've always had trouble with," added Biron, 5-9 in his career against the Thrashers. "It just so happened that we skated really well. Defensively we were really good. That made us create chances offensively."
Keith Tkachuk had a goal and an assist, and Eric Belanger added a goal for the Thrashers, who had won six of seven but are 1-10-2 against the Flyers in Philadelphia.
"We seem to have their number," Sanderson said. "It seems like every time we play them we are coming off a disappointment, so we try to bring our best game."
The Flyers had dropped two straight and three of four.
Ruzicka put the Flyers ahead 2-1 at 8:52 of the second period when he batted in a rebound of a shot by Sanderson, who skated the length of the ice and fired in a slap shot from the left side.
It was the second goal of the season and first in 25 games for Ruzicka, who has split time between the Flyers and Philadelphia of the AHL.
"That second period was by far one of the worst periods we've had since I've been here," said Tkachuk, acquired by Atlanta on Feb. 25. "Riverboat gambling, that's all that was. We gave up 3-on-2s in our own zone. That can't happen. This is playoff hockey."
The Thrashers are 6-2 since Tkachuk joined the team.
Sanderson made it 3-1 with his 11th goal at 4:48 of the third period when he flipped in a shot from the left side.
Belanger deflected in Tkachuk's shot at 14:28 to cut Atlanta's deficit to one goal.
Biron preserved the lead with a brilliant save of a point-blank shot by Scott Mellanby midway through the third period, and other stellar stops against Vyacheslav Kozlof and Pascal Dupuis in the closing minutes.
"A couple of mistakes in our own zone cost us the game," Atlanta coach Bob Hartley said. "I don't think we gave them very much. They took advantage of their chances."
Kari Lehtonen, who had won six of seven starts, made 33 saves. He kept the Thrashers even midway through the first period when he smothered a short-handed breakaway attempt by R.J. Umberger.
Hatcher put the Flyers ahead with a power-play goal with 43 seconds left in the first period. After the initial shot by Ruzicka bounced off his chest, Hatcher knocked in the loose puck.
"He wins a lot of puck battles," Flyers coach John Stevens said. "That was just a great effort by him on that play and a big turning point in the hockey game for us."
It was Hatcher's first goal in 126 games, dating to Dec. 3, 2005, when he scored at Nashville.
Tkachuk tied it 1:16 into the second period when he poked in a rebound of Niclas Havelid's shot, lifting the puck high over Biron's glove.
Philadelphia RW Mike Knuble returned after missing 12 games with a fractured cheek bone and orbital bone. ... Flyers LW Ben Eager was back after missing 11 games with a sprained ankle. ... Atlanta RW Marian Hossa's team-record, 11-game point streak (7 goals, 11 assists) ended. ... Atlanta C Jim Slater and D Steve McCarthy were healthy scratches. ... Philadelphia RW Scottie Upshall separated a shoulder when he was checked into the boards by Ilya Kovalchuk in the second period. He is expected to be sidelined about 10 days.