Niguez, 23, has emerged as a key player for club and country. This followed a troubled early spell across the city with Los Blancos’ academy, which he departed in 2008 after being bullied.
Ahead of Saturday’s first La Liga derby of the season between the sides, he was quizzed by Cadena SER about a potential cross-town switch.
He replied: “Real Madrid, for me it is unthinkable, it would be very, very difficult, almost impossible.”
Niguez signed a nine-year contract extension in July 2017, tying him to Los Rojiblancos until 2026.
“I do not know what is going to happen, I have until 2026,” he said.
“I signed it [the deal] knowing what there was and what there is. I am very happy.
“If someone outside [the club] offers you €20 million and here €5m, you have to think about it.”
Niguez has scored 29 times in 206 Atleti run-outs.
The 27-year-old Belgium wizard attracted interest from Real in the summer, especially after an excellent World Cup, that he might want a change of scenery from Stamford Bridge.
He has brought his form from Russia into the new Premier League season and scored a stunning winner as Chelsea came from behind to beat Liverpool 2-1 in the League Cup in midweek.
And Fabregas thinks that while Chelsea held all the cards in the summer window just gone, they may find it more difficult to stave off the European champions next year.
Hazard is under contract at Chelsea until 2020 and though contract talks have been ongoing for over a year, no agreement has been reached.
“It was an easy decision [to keep him], especially now, because at this stage how much can Eden cost?,” former Barcelona midfielder Fabregas told the London Evening Standard.
“Not many teams in the world can buy Eden Hazard. He still had two years left on his contract.
“Next year if he has one year left, that’s a different story. You don’t have as much power as a club. Eden is one of the best players in the world.
“But having two years left, especially how the market is, it’s basically impossible to sign him up. I don’t think it was that hard from the club.”
The France World Cup winner, who has had a series of bust-ups with Red Devils boss Jose Mourinho since his strong tournament in Russia, could have returned to the Turin club in the close season.
Pogba, 25, spent four seasons at the Juventus Stadium between 2012 and 2016 – winning four Serie A titles in the process.
And, apparently, Juve boss Mass Allegri was keen to add Pogba to his squad again even after Cristiano Ronaldo‘s arrival, though an actual bid nor fee was never made or discussed.
While Barcelona have also been linked with the central midfielder, it remains to be seen whether the Italian giants will rekindle their interest in January.