The chief reason swingman Thanasis Antetokounmpo of Greece decided to pass on a lucrative contract in Italy to play for $25,000 in the D-League for the Westchester Knicks was for this potential moment.

In convincing Antetokounmpo to stay in Westchester and not sign in Europe for a two-year, $500,000 pact, president Phil Jackson told the 2014 second-round pick there would be an outside chance of him being signed to the Knicks roster late in the season.

With the Knicks in the tank at a league-worst 10-43 with 29 meaningless games left and a roster spot officially open after Monday’s waiving of Amar’e Stoudemire, that golden opportunity has arose. Though Antetokounmpo has become a roster candidate, the Knicks are still very much on the fence right now about signing the older brother of Giannis “Greek Freak” Antetokounmpo.

All along, Jackson selected Thanasis with an eye on the 2015-16 season – he wanted a project to develop and bypassed more advanced college players with the 52nd pick in the draft.

Loving his high-energy defense and passion, the Knicks brass wants the 6-foot-7 perimeter defender for next season’s club, but feel he may be better off staying in Westchester. At age 22, he’s still a project whose basketball IQ and shot-making ability need to increase.

Another matter is finances. If they sign him now, he would be regarded as a second-year player next season and his contract would be worth $850,000 – or $320,000 more than rookie scale.

“Of course, that’s my dream, to play in the NBA,’’ Antetokounmpo told The Post on Monday, one day after finishing second in the D-League Slam-Dunk contest at Barclays Center.

“If I was to get that chance to go to the next level, I’ll put all my heart into it and give everything into it. Even from not playing at all to being a good teammate to being the guy who plays 40 minutes, I’ll do whatever it takes for the team to win.’’

Antetokounmpo’s Greece-based agent, Nick Lotsis, told The Post on Monday he spoke to GM Steve Mills last week.

“We have not heard anything today,’’ Lotsis said. “We had a discussion with Steve Mills with the past week. There was no clear indication about whether he’ll be there for the remainder of the season or if they are thinking next season. He said he’s thinking seriously about Thanasis for the team’s future. I don’t think it’s clear how the season finishes.’’

Either way, Antetokounmpo, whose D-League Knicks play in Delaware on Wednesday, has no regrets about snubbing Europe. Lotsis said he still gets calls, but says Antetokounmpo is committed to this process.

“Of course I’m glad,’’ Antetokounmpo said. “I’m a kid, and money really doesn’t matter. People who know me know I would prefer to play the next level, and if they said you’d have the same salary as the D-League or play for free, I’d still say yes. That’s who I am.’’

Thanasis, whom Jackson nicknamed “Tenacious’’ during Knicks summer league action, is averaging 13.7 points, 6.0 rebounds and 1.5 blocks in 32 minutes. He’s a terrific athlete, but was had a lot of foul trouble against advanced competition in the summer league.

“I think I’ve grown a lot,’’ Antetokounmpo said. “I think I get better every day. If we’re down, I never give up. I play hard to the end of the game.’’

He doesn’t have the skill level of his younger brother Giannis, the budding Bucks star. Last month, Giannis said his brother deserves to be signed, especially because of the Knicks’ losing record. Thanasis assisted Giannis in the NBA Slam Dunk contest and Giannis returned the favor in Sunday’s D-League event.

“It was a brother showing his love,’’ Thanasis said. “I think he’s really proud of me and knows I really work hard.’’