TIME: Saturday, 7 p.m. EST.
Atlanta has won eight of its last 10 - all with Lehtonen in goal - and is in ninth place in the Eastern Conference, one point behind Montreal.
The Thrashers, who has seen their point total rise in each of the last three seasons, started this season with 10 losses in their first 14 games. That included a four-game losing streak in which they were outscored 22-2.
Starting with a 34-save effort in a 2-1 win over Ottawa on Feb. 9, Lehtonen - the second overall pick by Atlanta in the 2002 entry draft - has a 2.04 goals-against average and .937 save percentage. Prior to the win against the Senators, Lehtonen was just 7-9-0 with a 3.08 GAA and .893 save percentage.
Lehtonen made 28 saves Thursday in Atlanta's 4-2 win over the New York Islanders.
"When you have a goalie like Kari back there, you know that if you play good defense you keep the team on the outside," said Atlanta defenseman Andy Sutton. "He is going to stop anything that comes his way. There is definite confidence back there."
Lehtonen has never faced the Flyers in his career, and Atlanta has just four wins in 23 games in the all-time series against Philadelphia.
Philadelphia ends a four-game road trip with this contest, and is looking for its second road win in nine games.
The Flyers lost 6-3 to Tampa Bay on Friday to fall to 3-5-1 since the Olympic break ended.
"What's disappointing is we had a lot of effort," Philadelphia coach Ken Hitchcock said. "We made some mistakes. You don't want to waste efforts like we had tonight."
Peter Forsberg scored Friday, snapping a season-high four-game scoring drought. Forsberg has a six-game point streak against the Thrashers, though, with one goal and nine assists in that span.
Simon Gagne, the team's leading goal-scorer, has seven goals in a five-game streak against Atlanta.
Goalie Robert Esche, who allowed five goals on 24 shots on Friday just one game after recording his first shutout of the season, is unbeaten in his career (3-0-1) against Atlanta.
STANDINGS: Flyers - 82 points, 2nd place, 2 PB, Atlantic Division. Thrashers - 70 points, 3rd place, 26 PB, Southeast Division.
TEAM LEADERS: Flyers - Gagne, 39 goals; Forsberg, 50 assists; Forsberg and Gagne, 67 points; Donald Brashear, 125 PIM. Thrashers - Ilya Kovalchuk, 42 goals and 82 points; Marc Savard, 56 assists; Sutton, 110 PIM.
SPECIAL TEAMS: Flyers - Power play: 17.4 percent (67 for 384), 18th in NHL. Penalty killing: 78.6 percent (305 for 388), 27th. Thrashers - Power play: 19.2 percent (84 for 437), 6th. Penalty killing: 80.0 percent (329 for 411), 25th.
GOALTENDERS: Flyers - Antero Niittymaki (19-12-6, 2 SO, 3.03 GAA); Esche (17-9-4, 1, 3.07). Thrashers - Lehtonen (15-11-0, 1, 2.69); Mike Dunham (4-4-1, 1, 2.79).
SEASON SERIES: Flyers, 2-1.
LAST MEETING: Dec. 28, Flyers 4-3 (OT). At Atlanta, Sami Kapanen scored 13 seconds into overtime after the Flyers twice rallied from one-goal deficits.
ROAD/HOME RECORDS: Flyers - 18-11-4 on the road; Thrashers - 18-12-4 at home.