It was a rare off night for Kristaps Porzingis. Maybe it was LeBron James. Maybe it was the new contraption on his elbow.

With James hounding him at times, Porzingis fell short of his now-usual 30 points. And for the first time he wore a long white right elbow sleeve for his bursitis, a condition that may need postseason surgery.

Previously Porzingis, who has admitted to lingering swelling, had only donned the sleeve during practice so it wouldn’t affect his shooting motion. But after shooting just 7-of-21 for 20 points in the 104-101 Knicks’ collapse, he may ditch it. It was only the fourth time in the 12 games he’s played this season he didn’t score at least 30 points.

“It was for extra protection for the elbow,’’ Porzingis said. “It didn’t help as much. If I fell on it, it hits so hard, the little protection didn’t do anything.’’

Porzingis picked up two fouls in the opening four minutes and never got untracked. Though he scored 10 fourth-quarter points, he also missed two free throws with 2:27 left and 3-of-4 overall in the final 3:30. James made it a point of defending Porzingis in the second half and blocked one of his turnarounds.

“He’s obviously strong in the post,’’ said Porzingis, who entered the game averaging 30.2 points. “I should’ve used that better — my length. It was really physical. He is who he is. I should’ve been maybe smarter and make a better play. The respect will be earned in the future.’’

If that was a knock on the officiating, he didn’t specify. But Porzingis admitted to being too lax on James’ tiebreaking step-back 3-pointer over him with 1:43 left after which the King hopped about the court.

“I was giving him more space than I usually do,’’ Porzingis said. “He can knock those shots down. [You’re] not going to take away everything.”

Ramon Sessions was spared and believes he’ll still help the Knicks — and rookie point guard Frank Ntilikina.

To make room for Joakim Noah on the roster, the Knicks axed popular forward Mindaugas Kuzminskas and kept the demoted Sessions, who lost his starting point-guard job to Jarrett Jack after the season’s third game.

The Post reported Sunday the idea of keeping Sessions would be as point-guard insurance in case Jack, who has knee problems, goes down.

Sessions said he still believes he can help — even if he’s only played once since his demotion, and didn’t get into Monday’s loss.

“That’s one of the reasons they still got me here,’’ Sessions told The Post before the Knicks hosted the Cavaliers. “I could’ve been the odd man out but they kept me. I’ll continue to be ready for that time.

“I wasn’t really worried. If they did something and it was me, I’d deal with it. I’m still here. I’m looking forward to continuing what we have going on, whatever my role. I’m still a Knick and excited to be here.’’

Two weeks ago, president Steve Mills indicated Sessions could still be used as a mentor for Ntilikina, 19, even if the journeyman doesn’t play. Ntilikina has gotten support from his mates after LeBron James’ insulting comment that Dennis Smith Jr., selected ninth in this year’s draft, “should be a Knick.’’ The Knicks selected the Ntilikina at No. 8.

“We don’t pay it no mind,’’ Sessions said. “ We know what we have in Frank. Frank knows we all appreciated what he brings to the team and his growth. We talk and shoot together every day. I’m still here. I definitely still talk to the young fella.’’

Knicks coach Jeff Hornacek refused to talk about why Kuzminskas was deemed unworthy of the roster but admitted adding Doug McDermott in the Carmelo Anthony trade was a major factor. Kuzminskas, 28, was in the final year of his two-year pact, being paid $3 million.

Clarence Gaines Jr., then Phil Jackson’s top adviser and who is still with the organization, was behind his signing. Sunday, Gaines tweeted a good-luck message to Kuzminskas after the release.

“Kuz is a professional — a guy who came in every day and played hard even though this season when he got off to a tough start with being [injured],’’ Hornacek said. “We thought he was doing great. He’s improved from last year. He was getting better defensively. He’s getting stronger.”

The Post reported the Hawks, Lakers and Bulls are expected to have interest in Kuzminskas if he clears waivers.

Ex-Knick PG Derrick Rose, who missed Monday’s game with an ankle injury, never had a strong connection with Porzingis. He likes what he sees now.

“Of course, I think everybody’s surprised,’’ Rose said. “Hard work is paying off. He’s been busting his a– the last couple years, just trying to figure out the game. The game is probably slowing down for him.’’ Rose said he never saw the Anthony-Jackson feud in action, feeling they got along when “they interacted in the same space.”

Ron Baker injured his shoulder in a G-League game Sunday and was inactive again.