The young, athletic, swift Memphis Grizzlies put on a Garden clinic in the first half Wednesday with point guard Ja Morant as lead firecracker.

The Knicks made it a game in the second half, but in the end just avoided a nationally televised embarrassment in absorbing a 120-108 defeat to the red-hot Western Conference power.

Surging Evan Fournier (30 points, 8 of 12 from 3) and Mitchell Robinson (14 points, 11 rebounds, eight blocks) were sensational, but the Knicks didn’t defend, rebound or get enough clutch play from Julius Randle.

The Grizzlies (37-18) are what the Knicks aspire to be. The 24-28 Knicks now head onto a murderous five-game western trip that will make or break their disappointing season.

Morant finished with 23 points and nine assists. He had plenty of help and the Grizzlies proved to have too many young weapons to handle.

“No disrespect to the Knicks, I feel like they are a good team with some great pieces,’’ Morant said. “It is just finishing the puzzle pretty much but that is what we are trying to do too.’’

Memphis’ Ziaire Williams, the rookie lottery pick out of Stanford, had a career-best night with 21 points. Jaren Jackson Jr., whose father works for the G-League Westchester Knicks, looked terrific in lighting it up from 3, and finished with 24 points.

Coach Tom Thibodeau said the Knicks’ “defensive transition” killed them in the first half before they shored it up. But they couldn’t rebound in the second half.

“Offensive rebounding cost us in the fourth quarter,’’ Thibodeau said. “Twenty five second-chance points. It’s hard to win like that.’’

When asked if the Knicks didn’t have the bounces go their way, Thibodeau said sharply, “You got to make them go your way.’’

“We were pretty confident, we were going to make a run,’’ Fournier said. “But I feel they got all the 50-50 balls tonight. Trust me, we tried.’’

Randle didn’t shoot well but posted nice numbers, nearly getting a triple-double with 18 points, 12 rebounds and nine assists. But the Knicks needed the 2020-21 version to beat this Grizzlies juggernaut.

During a timeout midway through the fourth quarter with the Knicks in range of an upset, Randle got involved in the Memphis huddle jawing with Desmond Bane. A double technical was called, and Randle picked up a second one in the final two minutes, leading to an automatic ejection.

The Grizzlies regained the momentum as Bane drilled a 3-pointer off an offensive rebound. Morant snaked to the basket for a layup and the Knicks were toast.

The Knicks felt they were closer than they really were as the Grizzlies led for the final 47 minutes.

“The way we evaluate it the transition points in the first half, we cleaned those up,’’ RJ Barrett said. “I needed to make a couple more free throws and get some more rebounds. We let them hit 3s. We played good initial defense the whole game. We played well offensively so it’s a tough one.”

The Knicks also got nothing — literally — from point guard Kemba Walker, scoreless for the second straight game as the Knicks look to deal him at the Feb 10 trade deadline. Walker was 0-for-4 in 17 minutes.

“He’s a proven scorer in this league,’’ Thibodeau said. “Players are going to go through different things. I just want him to shoot when he’s open. If you’re not shooting well, find a different thing to help us with.’’

Memphis took a 64-52 lead after a first half full of highlights. The Grizzlies were up by as many as 19 points as Morant poured in 15 with his dizzying drives and chatted up celebrity row.

Any Knicks turnover was parlayed into a highlight-reel Memphis dunk. During a two-minute span, Morant fed rookie Williams for a wild alley-oop slam followed by Williams lofting a lob for Morant for a fast-break jam.

The Knicks were no match but at least they have Fournier coming around.

“He’s in a good rhythm now,” Thibodeau said. “Teammates are doing a good job searching him out. If they’re loaded up on the strong side with Julius, the back side is open.”