Argentine legend Diego Maradona believes that his son-in-law Sergio Ageuro made a mistake by joining Manchester City last summer.
Aguero is believed to have had several options when he decided to leave Atletico Madrid prior to accepting an offer from City.
However, Maradona has insisted that Aguero would have been better suited to switching allegiances in Madrid.
"Kun [Aguero] has to play for Real Madrid. If he signed for them, it would be his big break," the Al Wasl coach told Argentine radio station Radio La Red. "Even though he is flying at City, the best thing would have been to sign for Madrid. He made a mistake.
"Now, as he is doing so well, it will be difficult to get him from City. They will want to keep him because [manager Roberto] Mancini has him very much in his plans.
"However, if Madrid want someone, they get them. Florentino has no limits. It's a question of convincing City, but not with money because they have plenty of that."
Earlier today City manager Roberto Mancini ruled out the possibility of selling Aguero.