The Nets saw their modest winning streak come to an end Thursday night at Barclays Center, blowing a late lead in a 123-110 collapse against the also-tanking Jazz.

In what promises to be a league-wide tank-a-thon, whoever is the most committed may win.

And the Nets showed some signs of strategic long-term commitment, resting Michael Porter Jr. in a clash that could have real implications in the all-important draft lottery.

The Nets fell to 5-17, now tied for fourth in the lottery odds with the Kings.

The Nets hit just 11 of 42 from 3-point range, and imploded down the stretch,

Danny Wolf (2) defends during the Nets’ Dec. 4 loss to the Jazz. Charles Wenzelberg

After building a 90-79 lead with a half-minute left in the third quarter, the Nets collapsed and shot just 36.8 percent in the fourth, including 2 of 11 from deep.

They coughed the ball up seven times in the final period and got outscored 14-0 off turnovers to turn what looked like a third straight win into a galling defeat.

“It was a complete disconnection,” coach Jordi Fernández said. “I don’t care about the fatigue or whatever you want to call it. You have to stay focused and locked in. This is the NBA.

“I know the back-to-backs, we’ve been really poor. [On Thursday,] we played hard for three quarters, and then in the fourth, it’s been a disaster, collectively. It was the energy and then the body language, and we have to be all better.”

The Nets led by as many as 15 points, and it was still 90-79 with :31 left in the third.

But that’s when they went ice-cold without Porter’s scoring.

They allowed as 25-8 extended run that flipped an 11-point lead into a 104-98 hole.

“We went into the fourth up 11, maybe something like that, and then they cut it real quick. And it was tied, and then they ended up making shots. So, I mean, we couldn’t get a good shot when it comes to it,” said Noah Clowney, who led the way with 29 points in Porter’s absence.

He got to the line and went 10 of 12 from the charity stripe, but admitted he slowed the offense down having to cut and play in Porter’s position with the veteran resting his back.

Being the go-to option is a new experience for the 21-year-old Clowney, and it’s a learning curve.

Noah Clowney dunks the ball during the Nets’ Dec. 4 loss. Charles Wenzelberg

It may happen more and more.

Despite improved play, the Nets aren’t changing lanes.

They’re still full speed ahead with their tank.

But Porter had been so good for them, he’s begging questions no one ever thought would need to be asked, much less answered.

A. Is he playing so well that he endangers the Nets’ tanking?

B. If so, do they have to trade him away to ensure their future rebuild, or can he actually become a part of that rebuilt future?

Lauri Markkanen dunks the ball during the Jazz’s win over the Nets. Charles Wenzelberg

Those are the sort of decisions that the Nets may have to start mulling sooner rather than later.

That inflection point may be approaching faster than expected.

They rested Porter to manage his sore lower back.

Without him, their offense couldn’t buy a basket when they really needed one.

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Ziaire Williams added 23 points and rookie Danny Wolf 17 with nine rebounds.

But they sorely missed Porter in the fourth quarter, when he has taken over and won games.

Lauri Markkanen had a game-high 30 for the Jazz, who are 8-13 and could owe their pick to the Thunder.

It’s top-eight protected, and they now sit ninth from the bottom in the league standings.

After Clowney rebounded a Keyone George miss, Wolf drilled a right-corner 3-pointer to put the Nets up 77-72.

Rookie Ben Saraf’s steal and breakaway dunk capped the blitz to make it 83-74.

And another Saraf swipe led to Wolf’s baseline drive that pushed it to 90-79 with 31.8 seconds left in the third.

The Nets imploded from there.