Islanders goaltender Ilya Sorokin looks on after Canucks defenseman Oliver...

Islanders goaltender Ilya Sorokin looks on after Canucks defenseman Oliver Ekman-Larsson scored in the first period of an NHL game at UBS Arena on Thursday. Credit: Kathleen Malone-Van Dyke

The Islanders gave one away — literally with turnovers — when they can’t afford missed opportunities. Making it worse, it came against Bo Horvat’s former team and with ex-Islander Anthony Beauvillier scoring the winner for the Canucks.

“I know them,” Horvat said. “They’re never going to quit and they didn’t again tonight. We blew that lead and they just kept pushing in the third period and we didn’t have enough pushback.”

The Canucks rallied from a two-goal deficit with three third-period goals to beat the Islanders, 6-5, on Thursday night at UBS Arena.

It snapped a four-game winning streak for the Islanders (27-23-5), who missed a chance to move into the Eastern Conference’s first wild-card position.

The Islanders committed 23 giveaways to the Canucks’ nine. A shaky Ilya Sorokin, coming off back-to-back shutouts, made 28 saves.

“I saw a lot of mistakes being made,” coach Lane Lambert said. “A lot of individual turnovers. Twenty-three giveaways, you’re not going to win a hockey game doing that. There were plays to be made and we didn’t make them tonight. It’s unacceptable at this point.

“When you’re up 4-2 in a hockey game late in the second period and you don’t win the hockey game, you feel like you’ve let something slip away. There’s a certain amount of frustration in that.”

Asked if that frustration is amplified with only 27 games remaining, Lambert replied, “That is correct.”

Horvat and Beauvillier both scored in their first games against their former teams. Horvat’s one-timer off Mathew Barzal’s feed gave the Islanders a 4-2 lead at 15:13 of the second period.

But Beauvillier tipped Brock Boeser’s initial shot for a power-play goal at 16:58 of the third period, which became the winner after defenseman Noah Dobson scored on the power play at 19:11 with the Islanders skating six-on-four.

“Being up 4-2, you’d like to think we can close it out at home against a team on a back-to-back,” said Brock Nelson, who tied the score at 2-2 at 14:34 of the first period to extend his career-high point streak to nine games. “For whatever reason, too many mistakes.

“This one hurts for sure.”

The Islanders acquired Horvat for Beauvillier, Aatu Raty — reassigned to the AHL — and a top-12 protected first-round pick on Jan. 30 and signed him to an eight-year, $68 million extension on Sunday.

“It was really weird,” said Horvat, who has goals in each of his two home games as an Islander. “A lot of emotions. You’re going against your buddies. I tried not to play like it. I would have liked to get that win.”

Beauvillier received a standing ovation as a video tribute featuring his overtime winner in Game 6 of the 2021 Eastern Conference finals against the Lightning in the last game at Nassau Coliseum was shown during a first-period stoppage. Beauvillier hopped over the boards to skate a quick lap, tapping his glove to his heart to acknowledge the crowd.

Both Horvat and Beauvillier were on the ice to start the game. Beauvillier was at the crease as defenseman Oliver Ekman-Larsson’s shot from the left point tied it at 1-1 at 11:44 of the first period, snapping Sorokin’s shutout streak at 144:00. Boeser made it 2-1 46 seconds later.

Kyle Palmieri’s rising wrist shot opened the scoring at 11:05 as the Islanders scored on two of their first three shots against Collin Delia (24 saves). Barzal’s one-timer gave the Islanders a 3-2 lead at 2:26 of the second period.

Nils Aman cut the Islanders’ lead to 4-3 at 16:04 of the second period and Elias Pettersson scored twice in the third period for the Canucks (21-27-4).

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