After earning a point Saturday night with a very makeshift lineup, the Islanders will have to go to the very end of the regular season Sunday night to learn whom their opponent will be in the first round of the playoffs.

A handful of eager new faces helped the Isles get that point in a 4-3 overtime loss to the Sabres at Barclays Center. A regulation loss would have clinched a first-round playoff matchup with the Panthers, but John Tavares tapped in his 33rd goal of the season with 6:26 left in regulation to tie it.

Brian Gionta’s second goal of the game 2:46 into overtime left the Isles with one point, meaning that to leapfrog the Rangers, finish third in the Metropolitan Division and earn a first-round series against the second-place Penguins, they will need to beat the Flyers on Sunday night.

That’s perhaps not the ideal matchup, but that was of no consequence to the AHL call-ups and depth players who populated Saturday night’s roster. Eight regulars sat out against the Sabres.

“You want to show the game respect every time you step on the ice,” said Scott Mayfield, who scored his first NHL goal in the second period to give the Isles a 1-0 lead. “You have to prove yourself every time you’re here.”

Alan Quine scored his first NHL goal in his first NHL game after being called up earlier yesterday. His shorthanded goal was set up by fellow call-up Bracken Kearns, a 34-year-old journeyman making his season debut.

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“It was pretty cool to get the call last night, then to get a goal in the first game . . . It’s a surreal experience,” said Quine, who has 50 goals in three seasons with Bridgeport.

Also surreal was the reaction of the crowd as the lottery- bound Sabres inched ahead twice, with plenty of fans pulling for a regulation Islanders loss to ensure what might seem like the easier matchup against Florida.

“It wasn’t a great game; it wasn’t a terrible game, either,” Frans Nielsen said. “I think we had two very emotional games, in Washington and in the Garden, and this was a little tougher tonight. Whatever we get, it’s two incredibly tough teams. I don’t really know who fits us better. You play [Sunday night] and see what happens.”

The Islanders might want to rest a few more regulars Sunday night, when the Flyers visit Barclays Center after clinching the last wild-card spot with yesterday’s win over the Penguins. But the Isles are limited in the number of recalls they can make, so it might be a lineup similar to yesterday’s, which included Ta vares, Nielsen and Kyle Okposo.

Christopher Gibson made his second NHL start and had 22 saves. He might go right back in Sunday night or he might split the game with Thomas Greiss. Everything is on the table in the name of preparing the Islanders for the postseason, regardless of whom they play.

If so, they still will have plenty of hungry players seeking to be noticed.

“Every chance you get at this level, you want to learn and make the most of it,” Mayfield said. “As far as points or standings go, I can’t really pay attention to that. I’m not taking any nights off.”