Lionel Messi would be the first player chosen by retired legend Ronaldo if he could include a foreign player in Brazil's national team.
The 37-year-old World Cup winner said on Thursday that he had no problem with players switching allegiances if they hold dual nationality, reports Xinhua.
"If Messi did not play for Argentina, I would love to have him (with us). I would prefer Messi to Diego (Maradona), even though Diego is also my friend," Ronaldo said during a press conference in Rio.
Ronaldo's comments come after Brazil-born Atletico Madrid striker Diego Costa earlier this week confirmed his desire to play for Spain.
The move has been backed by the Spanish football federation (RFEF), which has already submitted a request for approval from football's governing body FIFA.
England midfielder Jack Wilshere stirred controversy this week by claiming only English players should represent the national team.
His comments followed reports that England's Football Association had sought to convince Manchester United winger Adnan Januzai to play for the country.
Januzai, 18, was born in Belgium and is also eligible to represent Albania, Kosovo, Serbia and Turkey.