In every corner of the dressing room, the Rangers seethed — at themselves.
The Rangers dropped the first of three meetings in 10 days with the Islanders, 5-3.
"I thought they were controlling most of the game," Rangers captain Ryan Callahan said.
Thomas Vanek's power-play goal with 4:38 left in regulation was the game-winner. Frans Nielsen added an empty net goal.
"Division games are huge this time of year," Islanders forward John Tavares said. "It's nice to beat these guys, [and we] probably played a really good, strong hockey game. I think from the puck drop, they got those two early goals, but I think for the most part we were the better team."
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The Islanders' top line of Vanek, Tavares and Kyle Okposo finished with seven points.
The long-time rivals took turns trading figurative body blows throughout.
Rick Nash opened the scoring 1:02 into the game by cutting through two Islanders and whipping a shot past Kevin Poulin. Exactly 10 minutes and five seconds later, Nash scored his second of the game when Dan Girardi sprung him for a breakaway and he beat Poulin with a deke.
Nash has nine goals in the Rangers' last nine games.
"We've got a centerman that can feed both [of] his wingers and you [have] two wingers that have speed and skill," Rangers head coach Alain Vigneault said of the Nash-Derek Stepan-Chris Kreider line. "It should be an effective line and it has been for us."
Matt Martin cut the deficit in half with his third of the season at 17:22 of the first, but Chris Kreider put the Rangers up 3-1 with a power-play goal at 9:31 of the second.
"I don't think it felt like a 3-1 game at the time," Callahan said. "We got off to that lead but then we have to try and grab control of that hockey game. We need to up our intensity, our energy [and] for whatever reason we didn't do it."
And that's when it fell apart.
Thomas Hickey one-timed a diagonal, cross-ice feed from Kyle Okposo to cut the deficit to 3-2 at 13:22 of the second and Colin McDonald tied the game a 3-3 three minutes later.
"You're up 3-1 and you think maybe you can get through this period and play a good solid third but we didn't," Brad Richards said. "We made some mistakes. Some nights other teams will capitalize and some nights you get away with it. We didn't get away with it."
The Rangers did not have the services of Henrik Lundqvist because of an undisclosed illness, so the organization signed free agent goaltender David LeNeveu, who played for AHL Providence and AHL Hartford this season.
Cam Talbot started for the Rangers and made 32 saves. Kevin Poulin finished with 30 saves.
"Goaltending has not been our issue this year, I'll tell you that," Tavares said. "Great job by [Poulin] to shut the door. [He] had to make some big saves and can't ask for much more than that."
Follow Rangers beat writer Denis Gorman on Twitter @DenisGorman.