"Almost to a man, I think our game was at another level tonight," said Penguins coach Dan Bylsma.
Left winger Jussi Jokinen also added a power-play goal late in the third and center Evgeni Malkin scored an empty-netter with less than a minute remaining to seal the win.
The Rangers, losers of eight consecutive Game 2s dating back to the 2011 postseason, have now lost 13 straight games in which they had a series lead.
The game got off to a rocky start for the Penguins, as they had to kill three Rangers power plays before the game was 10 minutes old. The Penguins' penalty killers were stout, but the New York power play was also inept; mustering only two shots in the three opportunities. In fact, the Rangers are now 0 for their last 28 power-play attempts.
"It could have given us some momentum," said Rangers coach Alain Vigneault. "We didn't finish. I've got to find the right trigger points here to make it work and we'll spend the night trying to figure it out."
The Penguins broke the scoreless stalemate at 10:26 of the second period. With Letang down from his normal position along the blue line, he corralled the puck and attempted a pass from the right wing faceoff dot to left winger Chris Kunitz streaking down the slot. The pass was deflected up by the stick of sprawling Rangers defenseman Dan Girardi and past Rangers goaltender Henrik Lundqvist.
"I thought (Kunitz) had it," said Letang. "It looked like it deflected off his stick, but I think he told the referee. We'll take it, it doesn't matter who got it."
Malkin picked up the primary assist on the goal to tie him with Kevin Stevens for fourth place on the Penguins' all-time playoff points list with 106.
While the Rangers' power play continued to struggle, it was the Penguins' power play that sealed the game for them. Right winger James Neal fired a slap shot off the pads of Lundqvist that deflected right to the stick of Jokinen at the bottom of the right wing faceoff circle. Jokinen wasted no time in roofing the puck over the down-and-out Rangers netminder at 16:30 of the third.
"They were desperate. They knew they had to win this game," said Rangers right winger Martin St. Louis. "We matched it for a little bit, but we didn't match it long enough."
Fleury turned aside all 22 Rangers shots to earn his 50th career playoff win.
"I just tried to stop the next one; I tried to keep us in the game," said Fleury.
Lundqvist made 32 saves, many of them spectacular, in defeat.
"(Lundqvist) was their best player," said Jokinen. "He made some great saves and gave their team a chance to win. We know he's an elite goaltender but even how good he is we have to keep putting shots on the net and finding those rebounds."
Game 3 is set for Monday night at Madison Square Garden. The game will be New York's fifth in seven days.
NOTES: The back-to-back games Sunday and Monday mark the first time Pittsburgh played back-to-back post-season games since Games 1 and 2 of the 2009 Stanley Cup Final. ... The Rangers' Game 1 overtime win marked the first time they opened a playoff series with an overtime win since Game 1 of the 1986 Patrick Division Finals. ... The winner of Game 2 won 12 of the last 16 series involving the Penguins. ... Heading into Sunday's contest, the Rangers were first amongst all playoff teams in blocked shots with 141. ... Scratches for the Penguins were D Brooks Orpik (undisclosed), D Deryk Engelland, C Jayson Megna, LW Tanner Glass, LW Taylor Pyatt, RW Chris Conner, and G Tomas Vokoun. ... Scratches for the Rangers were D Raphael Diaz, D Justin Falk, C Chris Kreider (hand), C J.T. Miller, and RW Jesper Fast. The official attendance was 18,638.