LAS VEGAS — Thursday night saw the Rangers relapse in grave fashion.

The two wins following their season-long losing streak felt like a distant memory as the Blueshirts got upended by the reigning Stanley Cup champions, the Golden Knights, in a 5-1 loss that lost its’ competitive feel after just five minutes.

Both these teams skidded through the halfway point of the season after strong starts.

It was only the Rangers, however, who appeared to still be sliding Thursday night.

“That’s a tough one,” head coach Peter Laviolette said after the game. “I thought our guys started with the right intentions and played hard the whole night. I hate the score. The game just kind of unraveled in the wrong way for us for [what] seemed like a group that was ready to play.”

In the first of two meetings with Vegas in a span of nine days and the first of a four-game road trip out west, the Rangers fell into a 4-0 hole through two periods before Mika Zibanejad cashed in on a carried-over power play 40 seconds into the third.

The Golden Knights put on a defensive clinic at times while making the most of the offensive opportunities given to them.

Such was the case for Vegas, who were without Jack Eichel, who missed his third consecutive game after undergoing knee surgery, and Adin Hill, the goalie who largely backstopped the club to lifting Lord Stanley seven months ago.

Capitalizing on three rush opportunities throughout the night, Vegas found holes in the Rangers’ structure and exploited them — as so many opponents have done as of late.

Rangers goalie Igor Shesterkin, who gave up four goals on 17 shots through 40 minutes, was nowhere near the savior his team needed him to be.

“Again, some of those, ‘holy s—t’ moments in the back of the net where we got five or six minutes where we were playing really well,” said Chris Kreider, who notched an assist on the Rangers’ lone goal. “Hemming them in and working to get chances and then they get one really good one going back the other way. … It’s hard when you’re not really setting your goalie up for success when that happens.”

Already trailing by two at the start of the second period, the Rangers struggled to cleanly enter the offensive zone, leading to little sustained time in the Golden Knights’ end.

When Braden Schneider was called for interference at the 16:31 mark, Golden Knights forward Ivan Barbashev scored his second of the game on the power play.

Just 25 seconds later, Kaedan Korzcak’s trailing shot deflected in off the stick of Keegan Kolesar.

It marked the eighth — yes, eighth — time the Rangers have given up two goals within 30 seconds this season.

The Rangers did everything but score in the first five minutes of the game, but the rest of the game belonged to the Golden Knights despite the visitors holding a 30-26 edge in shots.

Three of Vegas’ five goals — which included an empty-netter from former Ranger Brett Howden — came off the rush.

Such has become a detrimental trend recently, and the Rangers fell into an early hole because of it.

It’s the same habits leading to the same results for the last month and a half.

“There’s things that we do want to improve and we want to do better,” Zibanejad said. “But I’m happy that we have things to improve. We put ourselves in a spot to keep pushing the second half of the season, but we have things to improve and that’s a good thing for us to just keep going.”