Frank Ntilikina has been there, done that.

Injured, underappreciated, potentially a trade pawn for a future draft pick.

Ntilikina feels for Knicks point-guard colleague Dennis Smith Jr., who is out indefinitely with an oblique strain and disgruntled about his future.

“Dennis is a great player, good friend,’’ Ntilikina said after the Knicks ended the 2019 portion of their schedule with Saturday’s 107-100 road win over the Wizards.

“Seeing him down with injuries, it’s tough. I’ve been in the same situation. But I know mentally he’s really strong. Everyone knows Dennis Smith Jr. from the youngest age, he’s been balling so it’s just a matter of time. We’re all here for him. I don’t think it’s a huge problem.’’

While Smith has spoken in ominous tones about learning “how to dance in the storm,” Ntilikina is singing in the rain. It’s been a role reversal.

When Smith arrived in the Kristaps Porzingis trade last January, it figured to spell doom for the Frenchman.

Though he lost his starting job a week ago to point guard Elfrid Payton, Ntilikina is a mainstay in the rotation — a defensive stalwart who is slowly improving his 3-point shooting. He’s hitting 33.8 percent from 3, up from last season’s 28 percent.

In the second quarter Saturday, Ntilikina spearheaded the second unit with his defense and led the Knicks during an 18-3 run.

His scoring line was typical Ntilkina — not audacious but effective while scoring eight points. He was 1 of 2 from the field — both 3-point attempts — made all five of his free throws, notched five assists, four rebounds and had only one turnover. (Payton committed six turnovers.)

“That second unit — Frank did an outstanding job when he came in and gave defensive energy where he made deflections that led to run-outs,’’ interim coach Mike Miller said. “He was playing with pace and kept people involved.’’

It’s evident the Knicks are a better defensive squad with the Payton-Ntilikina tandem. The Knicks are 4-1 in games Smith has missed under Miller.

For now, Ntilikina is the defensive engine off the bench, entrenched and happy.

“I think we’re putting in more effort [on defense],’’ Ntilikina said. “We’re getting better on that side of the court but we have to be more consistent.At times we’re letting easy plays in transition go for layups. There’s also something we can do better.”

As 2020 is ushered in when the Knicks host the Blazers on New Year’s Day, Ntilikina said he sees his team on the rise despite a 9-24 record (5-6 under Miller).

“We’re all positive, trying to get better,’’ Ntilikina said. “Our schedule wasn’t easy in the first part of the season.”

Ntilikina and Smith were selected as lottery picks in 2017 at No. 8 and No. 9 respectively. It’s known GM Scott Perry had Smith higher on his board than Ntilikina when he worked in Sacramento.

However, Smith has regressed while Ntilikina has made strides. The Athletic reported inquiring team executives got the impression Smith was amenable to starting over — something Smith fiercely denied.

A source told The Post that Smith has not requested a trade. In fact, his new agent Raymond Brothers is close with Perry.

Things could change, but Smith is considered third on the depth chart as Payton/Ntilikina give the Knicks the defensive posture Miller wants.

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