Over time, the idea of a Syosset boys’ basketball playoff victory had receded into a distant memory. So it was entirely appropriate that an overflow crowd at the home of the Braves had to endure overtime — make that double-overtime — for some new history to be written.

Athletic department staff had to pull out a seldom-used section of bleachers behind the visitors’ bench to accommodate a late-arriving group of fans and the Syosset gym rocked, even though most of the crowd was students not yet born the last time the school posted a playoff win.

But Griffin Halpern and Jacob Wiener each sank clutch free throws in the final 25 seconds of the second extra period and No. 4 Syosset held off No. 5 Calhoun, 76-72, Wednesday in a Nassau AA thriller that produced the Braves’ first postseason victory since 1991, according to coach Greg Cardona.

Halpern scored 29 points, Robert Kula scored 22 and Wiener added 12 as the Braves improved to 18-2 and will face No. 1 Uniondale in a Nassau AA semifinal on Tuesday at SUNY-Old Westbury at 5 p.m. The Colts finished 18-3 and got a terrific game from 6-7 senior Patrick Gardner, who scored 30 points and blocked eight shots. Jalen Rosemond added 22 points.

“Every possession was so important so we just had to dig in on defense, get open and take good shots,” Halpern said.

Frequently, the best shots Syosset got came at the free-throw line, as the Braves were not shy about driving, even with Gardner in the middle. They sank 24 of 27 free throws, including 8-for-8 in the overtime periods.

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Halpern missed the last shot of regulation, an up-and-under layup in which he beat Gardner off the dribble, and a fadeaway jumper at the buzzer that ended the first overtime. “I probably should have passed the ball on that one,” Halpern said.

Halpern hit a reverse to open the first overtime, but Rosemond answered with a driving bank. Wiener hit both ends of a 1-and-1, but Rosemond matched him with another layup.

Calhoun gained its only lead of the extra periods on Corey Jones’ putback and the Colts tied it at 70 on Gardner’s floater with 2:36 left. That’s when Syosset gained some breathing room on a layup by Wiener and two free throws by Halpern with 25 seconds left that made it 74-70. Calhoun’s Kevin Hannon drove for a basket with 12 seconds left, but Wiener sealed it with two more free throws with nine seconds remaining.

“We shoot really well from the foul line at home,” Halpern said. “Probably about 80 percent. Our guys did a great job under pressure.”

They were under the weight of history, too, so you could say it was about time.