After a tranquil summer by Real Madrid's standards, it is thought that 'Los Blancos' may be considering loosening the purse strings somewhat come January and should they do so, Ronaldo is in no doubt as to who would be a good fit in the Spanish capital.
According to 'Don Balon', the 32-year-old has told Perez to sign his international team-mate William Carvalho.
Carvalho was rumoured to be close to joining West Ham in the summer, only for the move to fall through, leading to a few colourful criticisms of West Ham's owners from members of the Sporting Lisbon board.
Ronaldo is thought to be a big fan of Carvalho's versatility and ability to play either in defence or in midfield and he feels that the player would be an excellent addition to the club's squad.
Zinedine Zidane's side have endured a torrid start to the new season, with La Liga leaders Barcelona already possessing a seven point lead over Real at this early stage of the campaign.
Whether Perez makes a move for Carvalho is a different matter though, with Real already boasting the talents of Casemiro and Marcos Llorente as defensive midfield options.
However, knowing how much weight Ronaldo's recommendation gives, it would be no surprise to see Carvalho in a Real Madrid shirt in the not too distant future.