Kristaps Porzingis became the tallest cheerleader on the planet late Saturday night.

The 7-3 rookie, rendered ineffective because of what he acknowledged was mental and physical exhaustion, was on the bench for the final 16:39 against the Trail Blazers but was up rooting for his teammates down the stretch. He watched Carmelo Anthony put the finishing touches on a 37-point night and a 112-110 win in Portland that snapped the Knicks’ losing streak at four games.

It was an unfamiliar spot for Porzingis, who has been an early-season Rookie of the Year candidate. How do you say “rookie wall” in Latvian?

Porzingis said the schedule and travel caught up to him on this three-game road trip. He went scoreless for the first time, shot 0-for-6 and had three rebounds, three fouls and two turnovers against the Trail Blazers in what was easily his worst game as a pro.

“It wears you down just being on the road, playing game after game,” he said. “I think I prepared myself, did the recovery and everything. You still can feel your legs are not 100 percent. I tried to be in the best shape possible. But it’s tough.

“Just my legs aren’t feeling as good as they should feel. I don’t have an injury. I’m healthy.”

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Porzingis was happy the Knicks won. He also was happy that they don’t play again until Wednesday, when he’ll square off against the other leading Rookie of the Year candidate, Minnesota’s Karl-Anthony Towns.

“This is kind of the first experience of playing so many games and on the road and in six days, four games,” he said. “It’s tough for sure. But I got to get used to it. That’s the schedule and I know the team needs me every night. I’m just happy that when I wasn’t there, they still managed to win games.

“[I need] rest — mentally, physically. Just have a fresh mind for Wednesday.”

This is all new for the 20-year-old. He appeared in 50 games in Spain last season and totaled 1,072 minutes (21.4 per game). Porzingis has played in 25 games for the Knicks and totaled 683 minutes (27.3 per game). He’s also been asked to do more, is playing against better and more physical talent, and is traveling more than he ever has.

The game in Portland concluded a trip that featured three games in four nights. Porzingis looked gassed in the opener in Utah. Then again, all the Knicks did. They fell behind by 32 in the second quarter.

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Actually, except for some solid defensive activity on Sacramento’s DeMarcus Cousins in the fourth quarter, Porzingis had a forgettable trip. He shot 6-for-25 with 17 points and 13 rebounds in the three games. He’s had a few single games with better numbers than that.

In Utah, the Knicks were a minus-27 in Porzingis’ 13 minutes. In the final two games, they were minus-2 and minus-8 when he was on the court.

“Every player in the league goes through it at different levels,” coach Derek Fisher said. “A number of our guys were fatigued with it being a third game in four nights and the intensity of our schedule to start the year. For sure, rookies are going to feel it the most when you’re accustomed to playing the number of games we’ve played already over the course of sometimes an entire season in college. International play one or two games a week is nowhere near what this is.

“He’ll be able to come back and give us the energy he provides. He helps us even when he’s not jumping off the charts. We won’t make a habit of him not being on the floor. We just did what we thought was best.”

Porzingis often brings up something his brother Janis has instilled in him: “Champions have short memories.” Porzingis said it applies here, too.

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“I just got to find a quote to bounce back finally from having bad games,” he said. “That’s my mentality again. Have some time off, I need to rest from everything. Wednesday I have another chance.”