Stars center Tyler Seguin takes a shot and scores as...

Stars center Tyler Seguin takes a shot and scores as the Rangers' Zac Jones and Igor Shesterkin defend on the play in the third period of an NHL game in Dallas on Monday. Credit: AP/Tony Gutierrez

DALLAS — One had to know the Rangers were going to lose a game in regulation at some point. They weren’t going to go undefeated the rest of the season.

But after earning at least a point in 11 straight games and winning 10 of them, it was almost stunning to see them collapse the way they did in the third period Monday against the Stars.

The Rangers blew a two-goal lead, allowing six straight goals — five in the third period — in a 6-3 loss to Dallas at American Airlines Center.

The Rangers (12-3-1) brought a 2-1 lead into the third period, but Joe Pavelski’s rebound goal after 61 seconds of play tied it. Mason Marchment’s power- play goal at 7:06 gave the Stars (12-4-1) their first lead of the game and the Rangers had two goal challenges go against them in the period as they lost in regulation for the first time since Oct. 19.

“We were going to lose a couple [eventually],’’ Jacob Trouba said. “It got a little wonky in the third with the challenges and goals, I guess. I don’t think it’s anything that you really go crazy over. It was a bad period . . . just kind of an awkward, awkward period that didn’t go our way.’’

One more thing that didn’t go the Rangers’ way: Artemi Panarin’s season-opening point streak ended at a franchise-record 15 games as he was held off the scoresheet.

Marchment’s goal initially was ruled no goal by the on-ice officials, who said he had interfered with Rangers goalie Igor Shesterkin when he jammed in the rebound of a shot by Wyatt Johnston that Shesterkin had stopped but not covered.

The Stars challenged the call, and the Rangers have not had good luck with video reviews this season. This one was never likely to go their way, and it didn’t as the Stars took a 3-2 lead.

Tyler Seguin crashed the net, managed to get enough of a touch on a rebound in the crease and slipped it under Shesterkin to give Dallas a 4-2 lead at 8:24. The Rangers challenged this goal, too, alleging goaltender interference, but the challenge was a desperate one and never was likely to be successful. It wasn’t.

The Stars tacked on two late shorthanded, empty-net goals by Sam Steel and Roope Hintz to dirty up the score before Barclay Goodrow got a consolation goal for the Rangers with 15.2 seconds remaining.

“You lose a hockey game, you’re disappointed,’’ Rangers coach Peter Laviolette said. “You want to do better, especially when you have a lead. So that’s the frustrating part of it.’’

Asked how painful the loss was after the 10-0-1 streak, Chris Kreider said, “I think for us, the focus has really been on each individual game, so it’s obviously frustrating right now for us, thinking that we had an opportunity to come away with points, having a lead.’’

The Rangers had taken a 2-0 lead on goals by Vincent Trocheck (on a power play) in the first period and Kaapo Kakko (his first point in 11 games) in the second period. But the Stars got that goal back less than a minute later when Jamie Benn finished a three-on-one break for his fourth goal of the season at 14:23, pulling Dallas within 2-1.

After that, things seemed to fall apart for the Rangers.

“We just got too loose out there, I think,’’ defenseman Ryan Lindgren said. “We gave them too much. We relied on Shesty too much there, especially in the third — a little bit in the second, too. We just weren’t good enough defensively.’’

After outshooting Dallas 16-7 in the first period, the Rangers were outshot 10-7 in the second and 19-10 in the third.

“They tilted it pretty good in the second,’’ Kreider said. “They were sharper in those little nuance things tonight that lead to prolonged zone time and chances.’’

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