Islanders' Kyle MacLean, left, celebrates his first-period goal against the...

Islanders' Kyle MacLean, left, celebrates his first-period goal against the Colorado Avalanche with teammate Ryan Pulock at UBS Arena on Thursday. Credit: Jim McIsaac

This wasn’t about Brock Nelson coming back to UBS Arena for the first time. It was about preventing the NHL-best Avalanche from coming back and ensuring just their second regulation loss.

The Islanders opened a four-goal lead in the second period before giving up two goals in one minute, 25 seconds to the most potent offense in the league. The Avalanche continued to press in the third period but the Islanders limited the Avalanche’s speed advantage enough with their neutral-zone work and ended a seven-game homestand with an impressive 6-3 win on Thursday night.

Mathew Barzal had a goal and two assists and Ilya Sorokin made 35 saves as the Islanders (15-10-3) ended a 3-3-1 homestand with consecutive wins over the conference leaders, including Tuesday’s 2-1 victory over the Lightning.

The Avalanche (19-2-6), who gave up a season-high in goals, had a 17-game point streak (14-0-3) snapped. Nelson, traded to the Avalanche on March 6, had an assist and he was given a first-period standing ovation during a video tribute highlighting his 13 seasons with the Islanders.

Barzal’s power-play goal on a highlight-reel stickhandling move through the slot, made it 5-2 at 18:46 of the second period. Defenseman Adam Pelech had made it 4-0 on a shot from the left that goalie Mackenzie Blackwood (36 saves) let slip through his glove at 7:59 of the second period.

But Valeri Nichushkin used his body to deflect defenseman Sam Malinski’s shot from the right point past Sorokin 40 seconds later and Martin Necas added a second goal at 10:04 on a puck that deflected in off Islanders defenseman Travis Mitchell’s skate.

Shortly after a first-period video tribute with highlights of Nelson’s time on Long Island, Anders Lee tied Nelson for fifth on the Islanders’ all-time goal list with 295. Lee, lifting a wrister from the right circle off Barzal’s cross-ice feed, made it 2-0 at 18:20. Bo Horvat banged in a rebound from the slot to make it 3-0 at 6:58 of the second period.

Kyle MacLean had given the Islanders a 1-0 lead at 5:56 to finish a strong shift from the fourth line, waiting out a long challenge from the Avalanche that Marc Gatcomb interfered with Blackwood by getting his stick stuck in the goalie’s right pad and trying to yank it free.

The Avalanche skated six-on-four after Blackwood was pulled for an extra skater and defenseman Scott Mayfield was whistled for tripping at 16:42 of the third period. The Islanders killed off the penalty and Casey Cizikas capped it with an empty-netter.

But, in the end, it earned the Islanders’ Patrick Roy his 200th career coaching victory, including his Avalanche tenure from 2013-16.

Notes & quotes: Top-six right wing Jonathan Drouin was a late scratch after participating in the morning skate and pregame warmups because of a lower-body injury. Marc Gatcomb drew into the lineup . . . Center Jean-Gabriel Pageau (upper body) missed his sixth game but participated in the Islanders’ morning skate in a non-contact jersey for the second straight time. Coach PatrickRoy said he expects Pageau to travel with the team for this weekend’s back-to-back in Tampa Bay and Florida. “I don’t know if he’s going to play a game or not,” Roy said. “We haven’t put a time frame on it. We’re going to make sure that he’s 100% when he comes back.” . . . This weekend is the dads’ trip, though some brothers are going as well . . . Goalie Ilya Sorokin started for the third straight game and for the fourth time in the last five matches . . . Defenseman Adam Boqvist remained a healthy scratch.

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