Eden Hazard claims Mariano Diaz was instructed to vacate the No.7 shirt for him upon his arrival at Real Madrid over the summer.
Hazard left Chelsea to join Madrid in an £89 million ($116m) deal on June 7, bringing to an end a hugely successful seven-year spell in the Premier League.
The 29-year-old had long been on Zinedine Zidane's radar, with rumours over his future often overshadowing his performances on the pitch during his final few seasons with the Blues.
Hazard was initially touted as a replacement for Cristiano Ronaldo - who joined Juventus in 2018 - which was reflected in Madrid's decision to offer the Belgium international the shirt worn by a five-time Ballon d'Or winner at Santiago Bernabeu.
The former Chelsea talisman claims he requested to wear No.50, with his preferred No.10 belonging to Luka Modric, but the Blancos insisted that he follow in the footsteps of legends such a Ronaldo and Raul Gonazlez.
During an interview with Sport/Foot magazine, Hazard explained how Mariano was told he had to give up his No.7 shirt for him when he touched down in the Spanish capital.
"At first it was from Mariano. I didn't want to go ask him. It's not my style. I knew that 10 was Modric," he said.
"At Chelsea, I took the 17. Lucas Vázquez has it. I was free to have 16 but I didn't want to.
"I said: 'Give me 50'. And the club told Mariano: 'You have to give Eden the 7' - you can't go higher than 25 in La Liga."
Hazard has only managed to score once in his first 13 appearances for Madrid, and hasn't played since November due to an ankle injury.
The mercurial winger acknowledges the fact that his numbers have not been good enough, while admitting that his contribution to the team's cause was minimal during his first couple of months at the Bernabeu.
"The only bad thing is the statistics. People just remember that. The first two months, what I did was not enough," he said.
"I said to myself: 'I can do better'. I really felt better after. I don't do everything right, but I try. The first two months, I said to myself: 'You are new, be simple'.
Hazard went on to discuss his experience of working under Zidane, describing the Frenchman as a "normal guy".
"He does not talk too much. The first two or three months were not as I wanted," he added. "He told me to stay calm. 'Be yourself,' he repeated. He is a normal guy.
"He doesn't complain about anything. He goes straight to the point. He loves his players. You feel that the group is happy that he is the coach.
"Even those who do not play. This is where you see that he understands what the players feel because he was on this side."