The Big Shot promised to pay back, and pay off.

The one-loss grace period is over. The Devils can’t wait any longer to start scoring or this could be their last home game of the season.

Fail to square their series with the Flyers tonight and they will head to Philly with the 0-2 disease that has killed 262 teams, leaving only 40 survivors.

Against that urgency, The Big Shot, Ilya Kovalchuk, uttered big words for someone who never has won a playoff game.

Kovalchuk was on the wrong end of the first turning point of this first-round series, eight minutes into Wednesday’s opener. The Devils had Kovalchuk, exactly whom they would want, in the slot, exactly where they would want him, poised to give them the opening lead with his laser-speed shot.

And Brian Boucher, the third-string goaltender who hadn’t won a playoff game in nine years, reached up with his mitt and essentially said “Look, ma, look what I found.”

“That was his highlight film. They’re going to see some of mine,” Kovalchuk grimly told The Post.

So instead of taking the early lead, the Devils were shaking their early heads. The tone was set and the Devils didn’t dent Boucher until 2:43 remained in the third, long after the Flyers had done enough for their 2-1 victory.

“After that save, he was a lot more confident, you could see it. He handled the puck more. But then when we scored, he wasn’t quite so sure any more,” Kovalchuk said.

The Devils outshot Philly 24-14 in the opener, and they say the recipe for winning tonight is simple.

“Just score goals,” said Travis Zajac, the lone Devil to do so Wednesday. “We’re playing well enough defensively.

“It’s not enough to get chances. We have to score.”

They also are going to have shake the tacit knowledge that they already have started the slide toward a third straight first-round exit.

“In the playoffs, you have to plant a doubt in the opposition,” Martin Brodeur said. “They’re flying high, they’ve beaten us 6 of 7 [this season].

“What we have to create is the thought that it’s not going to be an easy series.”

The Devils already have learned that. And coach Jacques Lemaire didn’t make it any easier on his Devils by failing to start and stick with the best combinations he had found during the regular season.

There’s an undercurrent around this team that has to do with Lemaire’s use of personnel. For example, in 10 minutes on their scoreless power play, Paul Martin played 7:49, Andy Greene 1:45; Kovalchuk 7:38, Zach Parise 6:14 and Zajac 6:08. Patrik Elias, the franchise’s all-time regular season and playoff scorer, and nowhere over-the-hill, had only 4:12 of extra man duty, and Jamie Langenbrunner less yet at 3:47, close to Dainius Zubrus’ 3:44 and Brian Rolston’s 3:39, and David Clarkson’s 3:21.

Rule No. 1 in the coaching manual is don’t mess things up. And often, the difference between genius moves and overcoaching is simply a bounce off a skate.

But right now, the Devils could use a little less attempt at genius, and a little more of sticking with what worked best this season, not the latest brainstorm.

mark.everson@nypost.com

