The Islanders had a chance to seize control of this series. Instead, they seized up.

Light-scoring Panthers defenseman Alex Petrovic beat Thomas Greiss with 10:35 to play to give Florida a 2-1 win Wednesday night and even the first-round series at 2, with Game 5 Friday night in Sunrise.

It didn’t feel like a one-goal game. The Islanders came out disjointed in a game that could have given them a 3-1 series lead. They put only five first-period shots on Roberto Luongo, allowing the Panthers to dictate the pace.

Even after Petrovic’s goal the Islanders were stymied, despite a power play with 3:33 to go. They pulled Greiss with just over a minute to play but could not beat Luongo, who made 26 saves.

“We didn’t play well enough to win,” Kyle Okposo said after the Islanders failed to win back-to-back playoff games for the 12th consecutive chance over the last 14 seasons. “They obviously came out and they just wanted it more. We had some spurts of good hockey but overall it wasn’t our best game.

“That’s disappointing.”

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John Tavares evened it with a power-play goal with 15.3 seconds left in the second period, answering Teddy Purcell’s power-play score for the Panthers at 15:18. The Islanders showed some life in that middle period which, as in Game 3, featured a video review that went the Islanders’ way.

Jonathan Huberdeau jammed the puck over the goal line along with Greiss’ pad at 10:45 of the second, with the young Panthers forward nearly injuring himself in the process. Referee Frederick L’Ecuyer ruled no goal on the ice, and a review initiated by the NHL situation room confirmed the call. Panthers coach Gerard Gallant then challenged the ruling, bringing another review and the same no-goal result — along with a nine-minute delay.

The Islanders had some of their better moments after that, with Josh Bailey stuffing a rebound under Luongo. But after L’Ecuyer disallowed it 90 seconds later, the game remained scoreless.

Other than that, however, the Islanders fell flat.

“The first period was probably the worst we played all year,” said Jack Capuano, who jumbled his forward lines early in the second with his team stuck on seven shots on goal. “You’re not going to win many games scoring one goal and getting offense from the same line every night. We need some other guys to pick it up.”

Even at 1 entering the third before another raucous, sellout crowd at Barclays Center, the Islanders were worked over in the opening half of the period. Petrovic, with two NHL goals in 112 games, got two Islanders defenders sliding before sending a wrist shot past Greiss’ stick for the winner.

“We had 20 guys who all played real good hockey,” Gallant said. “There wasn’t one guy who didn’t play hard. I think we’ve played real good all series.”

The Islanders cannot say the same, and now they have to dig deep to win a game on the road Friday to try and turn it back around. Tavares has three goals and seven points in the series and Okposo had six of the Isles’ 27 shots, but the rest of the team’s forwards have gone missing, especially the usually effective fourth line. Casey Cizikas and Matt Martin each took minor penalties in Game 4, with Purcell scoring while Martin was in the penalty box.

“We’re in a series, best of three,” Travis Hamonic said. “You just forget this one, it wasn’t our best, and think about what we need to do on Friday.”