Jaromir Jagr was flat on his stomach after scoring and cheers echoed through Madison Square Garden in what might have been his last home game with the Rangers.

New York staved off elimination, in what it hopes was the start of a monumental comeback, by beating the Pittsburgh Penguins 3-0 last night.

The building was in a frenzy after Jagr’s second-period goal broke a scoreless tie. He added an empty-netter, and Henrik Lundqvist did the rest with a perfect 29-save performance.

Jagr whipped a shot past Marc-Andre Fleury from the slot and then absorbed a high, heavy hit from Brooks Orpik that flattened the Rangers captain. He was assisted to the bench after a few anxious moments on the ice, but took his next shift as appreciative fans chanted his name.

The Penguins, who lost for the first time in eight playoff games this year, still lead the best-of-seven Eastern Conference semifinal 3-1. They will try again to finish off the Rangers in Game 5 in Pittsburgh on Sunday.

Only two NHL teams have come back to win after trailing 3-0, and none have done it since the 1975 New York Islanders against Pittsburgh.

Lundqvist, who allowed five goals to Pittsburgh in two of the first three games of the series, was on top of his game — his best moments coming against MVP finalist Evgeni Malkin. The second-year Penguins forward was denied by Lundqvist’s right skate at the post in the first period and then on a penalty shot in the second.

His name was chanted as the final moments ticked down, interrupted only when Jagr scored with 13.6 seconds left.

Jagr, who can become a free agent after the season, said after New York’s 5-3 loss on Tuesday that he had a feeling this Rangers team could do something special. His goal and assist on Brandon Dubinsky’s third-period, power-play tally was a good start.

The injury-plagued Rangers beat the Penguins at home for the fifth time in six games this season despite missing agitating-artist Sean Avery.