Jaromir Jagr and Michael Nylander made Kari Lehtonen long for his safe spot on the bench. And the Rangers’ top line needed less than a period to do it.

Lehtonen got the curious start over Johan Hedberg and then endured a thorough beating as the Rangers scored three times in the first period and cruised to a 7–0 victory over the Atlanta Thrashers that gave New York a commanding 3–0 lead in the Eastern Conference playoff series last night.

Nylander had his first playoff hat trick, and Henrik Lundqvist stopped 21 shots in his first NHL playoff shutout for the Rangers, who can advance to the second round as early as Wednesday at Madison Square Garden.

Lehtonen was touched for all seven goals on 35 shots. That was enough for the Rangers’ victory theme “Sweet Caroline” to play with 5:16 remaining over chants of “Sweep! Sweep!”

Jagr assisted on all three of Nylander’s scores and they teamed to set up defenseman Marek Malik for another that made it 3–0 at 12:26. But Nylander had the quickest strike of all when he wired a shot under Lehtonen’s shoulder 32 seconds after the opening faceoff on New York’s initial shot.

Rookie Ryan Callahan scored twice in the second period, defenseman Fedor Tyutin earned his fifth assist of the series, and Brendan Shanahan and Nylander added goals in the final frame.

Thrashers coach Bob Hartley, who went back to Lehtonen — the Game 1 loser — even though Hedberg played well in Game 2, called timeout after Malik’s goal. Lehtonen skated to the bench to regroup while Hedberg took a calm squirt of water.

The break only brought temporary relief to Lehtonen and the Southeast Division-winning Thrashers, who are on the brink of a sweep in their first playoff appearance.

That’s what happened a year ago to the Rangers when they got back in the postseason after missing seven straight times. Jagr and Lundqvist were hurt and New York was no match for New Jersey then, but this group earned the team’s first home playoff win since 1997.

Red, white and blue balloons fell from the upper reaches of the Garden during the national anthem, and the loud din hadn’t left the arena by the time Nylander really got the party started. Lehtonen stopped 34 of 38 shots in the series-opening 4–3 loss and was worse upon his return.

Hedberg made 37 saves in a much better performance Saturday, allowing a fluke goal on Sean Avery’s bank shot from center ice and Shanahan’s gimme off a perfect setup in front by Avery in the 2–1 defeat.

But Hartley announced Monday that he was going back to Lehtonen, the No. 2 overall pick in the 2002 draft and Atlanta’s presumed goalie of the future.

It didn’t work.

The skating and zigzagging play by Jagr and Nylander looked every bit like the Harlem Globetrotters on ice.

Jagr eluded Eric Belanger in the neutral zone then found Nylander behind the Thrashers’ defense for the first goal. Nylander then got to a big rebound of Marcel Hossa’s shot in the right circle to make it 2-0 at 9:45. When Malik scored 2:41 later, the only question left was how long Hartley would stick with the 23-year-old Lehtonen.

The answer was the whole way.

Callahan, who netted four goals in 14 games, got two postseason tallies just under 11 minutes apart in the second period to bust the game open.