With defenseman Matt Niskanen suspended for a game, Flyers coach Alain Vigneault inserted Shayne Gostisbehere into the lineup Friday in Game 6 of the Eastern Conference quarterfinals against Montreal.

Smart move.

Gostisbehere played a key role as the Flyers outlasted the gritty Canadiens, 3-2, and clinched the hard-fought series, four games to two.

Gostisbehere was on the third pairing and had Robert Hagg as his defensive partner, and veteran Justin Braun took Niskanen’s spot on the top pairing with Ivan Provorov at the start of the game. Phil Myers moved to the No. 1 defensive unit in the third period.

It worked. Barely.

Montreal had 71 shots attempts to the Flyers’ 35, and the Habs had a 33-17 domination in shots.

But Carter Hart made 31 saves, and the Flyers blocked 21 shots and gutted out the victory.

The revamped defense had some shaky moments, but they did just enough to win. They got contributions from everyone. Provorov had a goal and played nearly 25 minutes. Gostisbehere was plus-2 and helped set up the Flyers’ second goal, though he didn’t get an assist.

Myers played a career-high 23:47 and delivered six hits. Braun had six blocks – three fewer than Montreal’s entire team. Robert Hagg was plus-1 and blocked two shots. Travis Sanheim set up Michael Raffl’s game-winning goal and had two hits and two blocks in 22 minutes.

Minus Niskanen, most of the defensemen played more minutes than usual.

“Tonight, without Nisky and the minutes he logs, it had to be a committee,” coach Alain Vigneault said about the defense. ”There’s no doubt Provy and Travis Sanheim logged big minutes. Phil Myers logged big minutes, We had to give those guys a little more responsibility.”

Five of the defensemen who played Friday are in their early to mid 20s. Braun is 33.

“The young players are learning and growing,” Vigneault said. “They came up big for us at the right time.”

Gostisbehere, who overcame a pair of knee surgeries this season and regained his mobility, had played in three postseason games this year, including the round-robin tournament, and had a pair of assists and an even rating prior to Friday. He had played in Game 1 (a 2-1 win) and Game 2 (a 5-0 loss) in the series against Montreal, blocking six shots and registering a minus-2 rating.

“In the games we’ve used him, he’s played well. He has good jump,” Vigneault said prior to Game 6. “There’s no doubt that coming back from the [knee] surgeries set him back a little bit, but he put in a lot of time and put in a lot of effort. He’s had a real good attitude, a team-first attitude. I’m confident he’s going to play well for us.”

He did.

“He’s a warrior. He battles through adversity,” Provorov said. “He’s been here for a while. He’s a leader. Every time he’s on the ice, he helps our team a lot. Glad to have him in our lineup.”

“Ghost obviously wants to play every single night,” center Kevin Hayes said after collecting a pair of points and a plus-3 rating. ‘”When he’s not in the lineup, he’s working his ass off. He’s doing the things to get back in the lineup. His number was called tonight, and I thought he played great.”

Vigneault will have to take one of the defensemen out of the lineup when Round 2 gets underway against the Islanders. Niskanen will be back for Game 1 Monday.

The decision will be difficult. Depth does that.

Flyers-Isles schedule

The Flyers-Islanders series starts Monday at 7 p.m., and the teams will then have back-to-back games Wednesday (3 p.m.) and Thursday (7 p.m.).

Game 4 is next Saturday (noon), and Game 5 (if necessary) is scheduled for Aug. 31 at a time to be determined. If necessary, Game 6 would be played on Sept. 2 and Game 7 on Sept. 3.

Potentially, there are two sets of back-to-back games. TV is probably the reason.

The Flyers will face the Islanders in a playoff series for the first time since 1987. The Flyers have won three of their four playoff series against the Isles.

Breakaways

Hart finished with a 1.95 GAA and .935 save percentage in the series. He was named the No. 1 star in three of the Flyers’ four wins, and was the No. 2 star in their other victory. ... Jake Voracek led the Flyers in goals (4) and points (7) in the series. ... The Habs outscored the Flyers in the series, 13-11, marking the first time in franchise history that Philadelphia won a playoff round while being outscored. ... Flyers set a franchise record for fewest goals scored in a six-game series win. They scored 14 against the Minnesota North Stars in winning a 1973 series in six games.