Kari Lehtonen shut out the Rangers in the third period of Thursday night's 4-3 loss, but still the young goalie will be benched in Saturday's Game 2.
Lehtonen's low point of the game was allowing the critical fourth goal in the second on a rebound off his glove.
Coach Bob Hartley told Lehtonen, 23, on Friday that he will give Hedberg the start after the Thrashers lost home-ice advantage by dropping Game 1.
Lehtonen probably will be back as the starter in Game 3 in New York on Tuesday. Hartley said Lehtonen should be more relaxed after his first playoff game.
"I could feel that Kari wasn't as comfortable as he would like, but that's called experience," Hartley said. "You need to go through this at some point in your career."
Lehtonen already was looking forward to another chance immediately after Thursday night's game.
"For a guy like me, who has never experienced this before, it will help me," Lehtonen said.
Lehtonen's lack of experience didn't show early. The Rangers outshot the Thrashers 10-5 in the first 10 minutes, but Lehtonen stopped each shot before Jaromir Jagr's blast at the 12:50 mark broke the scoreless tie.
Hedberg, 33, set a season high with 38 saves in Atlanta's 2-1 overtime victory over the Rangers on March 16.
Hedberg is 10-10 in 20 career playoff games with Pittsburgh and Vancouver. He helped the Penguins advance to the 2001 Eastern Conference final.
Hedberg was 9-4-2 in 21 games as Lehtonen's backup this season, sporting a 2.89 goals-against average.
Hedberg will be challenged by the Rangers' Jagr, Michael Nylander and Martin Straka, who combined for two goals and four assists Thursday night.
Atlanta's top three scorers in the regular season - Marian Hossa, Ilya Kovalchuk and Slava Kozlov - were held without a point.
Hossa and Kozlov each attempted only one shot. Kovalchuk also was relatively quiet with only three shots, including none in the third, in his first playoff game.
The Rangers outshot the Thrashers 38-24.
New York built leads of 2-0, 3-1 and 4-2, keeping Atlanta in a constant comeback mode.
The Rangers, swept by New Jersey in the first round last year, grabbed their first playoff win since 1997 and continued the momentum built by their 17-6-6 regular-season finish after acquiring Sean Avery.
The Rangers may take little notice of Atlanta's change in the net.
"You don't look at who's in the net," Jagr said. "You just have to play your game."
New York's defence provided better support for Rangers goalie Henrik Lundqvist, who led the NHL with his 1.89 GAA following the all-star break.
Lundqvist was at his best in the final 1:11 on Thursday night, when he held off a Thrashers' power play. Atlanta pulled Lehtonen for a 6-on-4 advantage in a final attempt to reach overtime, but Lundqvist held off the challenge for his first playoff win as Kozlov's last-second shot was wide of the net.
"We had our chances at the end, but he did a good job blocking our shots," said Atlanta's Keith Tkachuk.
Tkachuk said the Thrashers would be better prepared for Game 2.
"It's a long series," he said. "We are going to get our chance again and be ready to go from the start.
"One game is not going to be the difference."