LAS VEGAS — The Vegas Golden Knights clinched their playoff berth on March 30.

Nearly three weeks later, they looked complacent as ever, minus the edge most teams bring into the postseason, as they dropped their Western Conference quarterfinal opener to the Winnipeg Jets, 5-1.

The Jets, meanwhile, clinched their playoff berth less than a week ago and skated onto Vegas’ ice inside T-Mobile Arena, in front of an announced crowd of 18,006, looking as if they’ve been in postseason mode for quite some time.

“Yeah, we’ve kind of been playing must-win games for a little while now,” said Jets right wing Blake Wheeler, who had a goal and two assists in the win. “I just think we’ve been through a lot in the last 12 months, so adversity-wise, we’ve kind of seen a lot. Playing important games down the stretch certainly helps, and having some success in those games to earn a playoff spot I think was definitely a benefit to our team.”

Kyle Connor also scored for the Jets, while Pierre-Luc Dubois added a goal an assist and Adam Lowry iced the game with two late goals.

Vezina Trophy candidate Connor Hellebuyck made 16 saves for Winnipeg.

“He made some big saves, especially early on, they had a couple of looks on our penalty kill,” Wheeler added. “Wasn’t the shot volume he’s used to seeing, but when we needed him, he made some huge saves.”

William Karlsson scored the lone goal for Vegas, while Laurent Brossoit made 26 saves in his first regulation loss all season.

After being outshot 21-15 over the first two periods, the Golden Knights’ offense become non-existent in the third period, putting just two shots on goal while the Jets pulled away.

“I think maybe at times were a little passive, and didn’t play as confident and just wasn’t our best,” Vegas center Jack Eichel said. “We got to be resilient here. It’s a seven-game series. We got to just come back and be better next game. I thought there were spurts there where we were good when we got pucks in behind their D, and played in their end. I think we just need to establish our forecheck a little better and be a little hungry on pucks and just raise our compete.”

It was the first playoff game for the Golden Knights in two seasons, after missing the playoffs for the first time last year.

The teams meet in Game 2 on Thursday, at 7 Pacific.

TURNING POINT: Vegas had a prime opportunity to grab momentum by tying the game late in the second period. Shortly after Karlsson’s goal cut Winnipeg’s lead in half, 2-1, Jets center Mark Scheifele was sent to the box for cross-checking Vegas’ Phil Kessel. But the Jets stymied Vegas’ power play and took their 2-1 lead into the locker room. Wheeler then extended Winnipeg’s lead to two goals just 3:53 into the third period, and the Jets never looked back.

“I think if you look across the playoffs, especially last night, and I haven’t seen all the games tonight, how important the power play and PKs have been. That’s a completely different feel to the game if we’re going in 2-2 going into the third period.”

WHAT WORKED: Vegas’ penalty kill, for the most part. The Golden Knights did a good job killing Winnipeg’s first two opportunities, both in the first period, and back-to-back. Shea Theodore hadn’t left the box before Zach Whitecloud was whistled for slashing, giving the Jets roughly four minutes with an extra skater. But the Golden Knights killed both, keeping the game scoreless. Not bad considering the Golden Knights finished the regular season with the 22nd-ranked penalty kill on home ice, and 19th overall.

WHAT DIDN’T: Vegas’ power play was downright awful, going 0 for 3 with the man advantage. Of their season-low 17 shots on goal for the game, only one came during their three power plays. The Golden Knights closed the regular season with just four goals in 32 attempts spanning 12 games. Dating back to Jan. 14, the Golden Knights are 12 for 93 (12.9%) on the power play.

STONE COLD: Vegas captain Mark Stone’s return to the ice for the first time since Jan. 12 wasn’t the rejoin he or the Knights probably hoped for. In 21:28 of time on ice, Stone finished with a -3, had two shots miss the target and had one turnover.

“I felt like I missed three months, obviously,” Stone said. “The pace of the game is ramped up at this time. So hopefully you just feel better and better going into the next game. But no excuses, right? I’ve been in this league long enough to know what needs to be done.”

WHAT’S NEXT: The Golden Knights have been in this position before, and have plenty of components on the roster from their last playoff team on this year’s squad. Sporting Tribune columnist Steve Carp details the importance of a Game 2 win.

“We’ve been in this position before,” Stone said. “Obviously the last couple seasons we’ve had slow starts to series, so, we’ve got enough veteran guys in here, enough guys who have won at this level to get this ship turned around.”