KC Ndefo is so big, so athletic, so strong that he is a handful of a defensive assignment even if he’s not hitting his jumper. When the 6-5 Elmont junior’s shot is falling, good luck.

Ndefo sank three three-pointers in the third quarter, when he scored 15 of his 26 points, and led No. 1 Elmont to a 76-55 win over No. 8 Floral Park on Thursday in a Nassau Class A quarterfinal. The defending state champion will face No. 4 Valley Stream North in a semifinal Wednesday at Hofstra.

“When KC’s on fire, we get him the ball most of the time,” combo guard Victor Olawoye said. “We look to him. Whenever he’s on fire, pretty much nobody in the county can guard him. So we look to him, and today he pushed us.”

Ndefo’s ignition began in the final seconds of the second quarter. After Conrad Ihaza nailed a deep three-pointer with 15 seconds remaining, Olawoye (10 points) grabbed a loose ball and fed Ndefo ahead of the pack. Ndefo elevated for a one-handed slam just before the buzzer, giving Elmont a 33-22 lead at the break.

“It was a momentum-builder,” said Ndefo, who had five dunks. “Possessions like that in a game, they boost our confidence leading into the half. We kept it through the half and kept it through the third and fourth quarters.”

Floral Park (16-5) held Elmont (17-4) without a point through the first three minutes of the second half but managed only two free throws by T.J. Cluess (23 points) in that span. Then Ndefo stole a pass and went coast to coast for another rim-rattling dunk. He scored on a putback, hit a three-pointer off the dribble and stepped into another three-pointer off a pass from freshman point guard Jevon Santos to give Elmont a 45-27 lead with 1:20 left in the third.

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But he saved his best for last in the quarter.

With about 30 seconds left, Ndefo cut down the right wing and caught a lob from Olawoye for an alley-oop. Elmont got the ball back after two missed free throws, and Ndefo beat the buzzer with a step-back three-pointer from the left wing.

“We just try to get him the ball when he’s open,” said Santos, who scored eight points and effectively pushed the pace. “When he’s hitting shots, he can’t be guarded. We’ve just got to give him the ball and he’ll get a bucket.”

Ndefo appreciates his teammates for that, especially Olawoye and Santos.

Elmont's KC Ndefo leaps as he celebrates basket with Victor Olawoye in Nassau Class A quarterfinal playoff game in Elmont, New York, on Feb. 23, 2017. Photo Credit: Patrick E. McCarthy

“They’re great,” Ndefo said. “I love playing with them. We’re trying to get to where we’re going. Playing with them is just great.”