Marcelo said the door is always open for Neymar to join Real Madrid as he insisted Cristiano Ronaldo does not own the European champions.
The futures of Paris Saint-Germain forward Neymar and five-time Ballon d'Or winner Ronaldo are dominating headlines heading into the World Cup in Russia.
Neymar is tipped to leave Ligue 1 champions PSG for Madrid just one season after his record-breaking transfer from Barcelona, while Ronaldo has been linked with a move away from the Santiago Bernabeu following last month's Champions League triumph.
While Marcelo wants Ronaldo to remain in the Spanish capital, the Brazil full-back said the 33-year-old will not determine whether international team-mate Neymar will arrive or not.
"Cristiano Ronaldo doesn't own Real Madrid," Marcelo said during a Brazil news conference. "If the president [Florentino Perez] wants somebody, he'll pick somebody. It's not like Neymar can't get in because Cristiano is in the team.
"I want Cristiano to stay, all players want it but one thing has nothing to do with the other. Real Madrid doors are always open for Neymar. The best players in the world should play in Real Madrid.
"I've already said that two, three years ago. I guess someday Neymar will play in Real Madrid. I don't know when."
Marcelo was also asked about Sergio Ramos and Roberto Firmino as the fallout from the Champions League final continued.
Liverpool and Brazil forward Firmino branded Ramos an "idiot" after the Madrid captain mocked the reaction to his challenges on Mohamed Salah and Loris Karius – whose two errors proved costly – in the 3-1 triumph in Kiev.
"I am only missing Roberto Firmino saying he got a cold because a drop of my sweat landed on him," Ramos told Spanish newspaper AS after he was heavily criticised for tangling with Salah, while he was accused of deliberately elbowing Karius.
Firmino did not appreciate Ramos' mocking tone and Marcelo weighed in, telling reporters: "I've known Sergio Ramos for 12 years and it's bad to win three straight Champion Leagues and see people talking that it was so because the goalkeeper was hit, or someone was sent off, or a penalty wasn't given.
"I guess it would be necessary to recognise more Real Madrid's three titles, with due merits, no other thing. People end up paying much more attention to a problem with the goalkeeper than all three goals we scored against Liverpool. We won Champions and people said it was the goalkeeper's fault, poor man, had to take a defeat as his responsibility, and not of all the team, in football these things happen.
"About Firmino and Sergio, I understood what Sergio said another way but people can interpret this as they want. I understood it as a joke from Sergio, everybody saw, there's a video with Sergio saying this. I guess it wasn't necessary to get at this point. I know Sergio for 12 years, I play with Firmino for four years, in the Brazilian squad.
"I won't give any opinions about it, but I see this like that. Anyone has your own opinion, you can say he's an 'idiot' or not but I consider it's necessary always to have respect regarding your fellow professional."
