After winning three of their previous four games against NHL heavyweights, the Flyers got decked by a lightweight Thursday night at the Wells Fargo Center.

Montreal 4, Flyers 1.

So much for the apparent momentum gained from the Flyers’ 4-3 overtime win Wednesday in St. Louis, the defending Stanley Cup champion.

“I think it’s natural when you play a top team in the league and have an emotional win, as much as you try to fight it, it’s going to be a little bit of a letdown” in the next game, defenseman Matt Niskanen said. “I think we were fighting that tonight. You certainly don’t want it to happen, and we have to find a way to get over that the next time it happens."

“Sometimes after an emotional win, it’s tough to get up [for a game] the next day, but there’s no excuses,” captain Claude Giroux said. “We didn’t play our game; we didn’t play well. That’s two points that we let go here.”

Coach Alain Vigneault didn’t want to talk about an emotional letdown.

“You know that word that starts with B?” he asked, referring to an expletive. “No. These are big games. There’s almost nothing separating teams. ... I understand emotionally, but points are the same. This game was worth two. The last game was worth two. You’ve got to get up for it. You’ve got to get yourself ready.”

Goalie Carey Price is having a disappointing season, but you wouldn’t have known it by the way he played, stopping 40 of 41 shots to carry the Canadiens.

“Some of the good looks we had, he made the saves look pretty easy,” Niskanen said.

The Habs got a pair of scores from Ilya Kovalchuk, the 36-year-old winger who had his 58th multi-goal game of his career. Kovalchuk secured the win by scoring on a blast from the high slot with 8:47 left in the third, giving Montreal a 4-1 lead -- and giving him 27 goals and 53 points in 52 career games against the Flyers.

The Canadiens signed Kovalchuk to a two-way deal for $700,00 earlier this month. He will get $70,000 if he is demoted to the AHL. He has seven points, including three goals, in seven games with Montreal.

Montreal scored goals 11 seconds apart to take a 3-1 lead early in the second period.

But not before Price, 32, reminded folks why he has been one of the league’s best goalies in his 13-year career.

With the game tied at 1-1, Price calmly outwaited Scott Laughton to make a move on a shorthanded breakaway, and he easily turned him aside with 18:30 left in the second.

Before the penalty ended, Kovalchuk scored on a rebound to put the Habs ahead, 2-1, with 17:52 remaining in the first. Just 11 seconds later, Artturi Lehkonen got position on defenseman Ivan Provorov and redirected Phillip Danault’s shot over Alex Lyon (36 saves) to give the Canadiens a 3-1 lead.

Lyon, recalled from the Phantoms on Wednesday because of Carter Hart’s abdominal injury, was making his first NHL appearance in about 13 months.

Rookie left winger Joel Farabee was demoted to the Phantoms on Wednesday to give the Flyers enough cap space to recall Lyon from their AHL team.

On Thursday, he returned and promptly ended a 15-game scoring drought by connecting on a rebound with 1:13 left in the opening period.

“It’s been a while since I last scored and it definitely felt good, but at the end of the day, it doesn’t really mean much when you don’t win," Farabee said. “…The puck kind of came out to me and I knew there was a lot of traffic and their goalie was probably going to be sliding out, so that’s why I went five hole.”

The Flyers’ lead lasted 18 seconds. With Lyon scrambling to get into position, Tomas Tatar (three points) scored from deep inside the left circle, knotting the score at 1-all.

Both teams were playing on the back end of back-to-back games. The Flyers (25-17-6) were coming off the dramatic win in St. Louis, and Montreal (21-21-7) got booed by its home crowd at the end of its 4-1 loss to Chicago.

Montreal, which lost its two previous games (both in overtime) against the Flyers this season, has been better on the road (12-9-3) than at home (9-12-4).

Conversely, the Flyers have been much better at the Wells Fargo Center; they took the league’s best home winning percentage (.773) into the night.

But Price was the difference. He took just a 2.87 GAA and .907 save percentage into the game, but has looked like his old self recently, stopping 112 of the last 114 shots he has faced.

Niskanen called Thursday’s loss a “missed opportunity.”

“We just have to regroup and come back with a better effort than we had tonight,” said Farabee, whose Flyers play Saturday against another team, the Kings, not in a playoff position.