Sam Carrick put New York ahead 1-0 on its first shot on goal at 2:24 of the first period, holding off Pittsburgh defenseman Kris Letang to tip in a point shot from Trouba. Carrick made his Rangers debut after signing a three-year contract July 1.
Will Cuylle appeared to extend the lead at 9:48 but his goal was overturned following a Penguins challenge for offside.
Lafreniere then made it 2-0 at 17:23. After taking a stretch pass from Panarin, he dragged the puck around a sliding Marcus Pettersson for a wrist shot to the blocker side from the left face-off circle.
“I think we came out pretty strong,” Jarry said. “Just got a little loose at times. A lot of odd-man rushes. If I make a save on that second one, I think it at least helps the guys stay in it. ... It’s obviously tough. It’s not the outcome you want.
“It’s a long season, though. So we have to find our legs. I think we’ll be better from this one. We’ll learn from it.”
Kreider pushed it to 3-0 at 19:48 with a wrist shot from the slot off a rebound from Trouba’s one-timer.
“We had to get through the first 10 or 12 minutes. 'Shesty' made some really big saves at that point,” Rangers coach Peter Laviolette said. “Then the last, I thought, maybe, eight minutes of the first period, I thought we turned it on offensively. Able to generate and were able to carry that through the second period as well.”