When the Rangers finally got on the power play Thursday night after nearly 120 minutes between chances, the Garden faithful gave a sarcastic cheer.

They weren’t the only ones upset at the lack of calls in the Rangers’ favor.

“It’s about time,” Rangers coach Gerard Gallant said following the 5-2 victory over the Penguins.

The Rangers, who finished the regular season ranked fourth on the power play, scored 21 seconds into their first man-advantage of the series against Pittsburgh on Tuesday. And on Thursday, finally given a second chance, they converted again, with Ryan Strome tipping Adam Fox’s shot from the high slot past Louis Domingue at 2:59 of the second period.

By the end of the night, the Penguins had incurred six penalties, though three came in the game’s dying moments — two of them when Jeff Carter skated into Igor Shesterkin at 17:56 of the third period. Still, the Rangers had their chances on the power play.

And they gave a reminder of why that is such an important factor in this series.

The first power-play unit was on the ice for the entirety of the man-advantage following John Marino’s cross-check until Strome finally scored. The same five were out there for nearly the length of Kasperi Kapanen’s holding penalty later in the second, pelting Domingue with pucks. None went in, but the sequence helped the Rangers retain momentum during a key moment in the game.

Gallant is not a coach who makes use of his bully pulpit often, and he didn’t go so far as directly criticizing the referees on Thursday night. But he clearly wasn’t all too happy with how things went in that department.

“You go back the last game and I thought we should’ve got more chances,” Gallant said. “And it didn’t happen, it was four to one [in power-play opportunities] last game and then tonight it didn’t start out real good either. I was disappointed. And then all of a sudden they started taking some penalties and our power play got a chance.

“So overall, it’s a tough job for the officials. Guys are playing hard and competitive, but right off the bat I thought they should’ve had the penalty on tripping the goalie, two or three shifts in. It wasn’t called and they get the next two power plays. You’re saying ‘here we go again.’ ”

He recognizes the obvious: that for the Rangers to win this series, they will need to get ample opportunities at five-on-four.

The first two games put that on display, albeit for entirely different reasons.

Gallant is much more pleased with Thursday’s version.

“I was pretty happy we finally got some chances,” he said. “For sure.”