Cristiano Ronaldo has said transfer fees in football have got out of hand and that a player of his calibre in the market would now sell for €300 million.

His transfer to Real Madrid from Manchester United in the summer of 2009 was a then world record £80m, but eight years later, Neymar left Barcelona for Paris Saint-Germain for €222m.

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Asked what he would likely be sold for now, he told Portuguese TVI: "Based on how football is nowadays? It's difficult to calculate.

"Today there is a lot of emphasis placed on potential and the football industry is different. I'm going to put aside [Portugal international Joao] Felix's [€120m transfer to Atletico Madrid from Benfica] case. Nowadays, any player is worth €100m having proved nothing, there is more money in football.

"A goalkeeper, a centre-back is worth €70m, €80m -- I don't agree. But this is the world which we live in, the market is like that and you have to respect it. Is there a football player that has more records than me? I don't think there is a player that has more records than me."

Ronaldo left Real Madrid to join Juventus for €100m last summer and, pressed on what his worth would now be, he added: "If I were 25, if a goalkeeper is worth €75m, a player that does and has done what I have done in recent years has to have a value of three or four times that, easily, but I no longer have that desire."

The 34-year-old also said "the challenge" of winning individual and collective trophies at the top level keeps him motivated to continue playing football. The Juve forward said he could retire next year if he wanted as he has amassed a fortune in wages, endorsements and investments yet the temptation is there to play until he's 41 as he craves more silverware.

"My motivation is my obsession for success, I admit it," he said. "But it is a good obsession.

"I know I'm already in the history of football. I know that I'm one of the best in my field but that is not by chance. I could end my career next year but I could also play until I'm 40 or 41.

"It's about the challenge. I still feel motivated to win individual and collective trophies, and if I wasn't, I would end it [career]. I have everything I want, I have an excellent family, I have spectacular businesses. From a financial standpoint, I'm very well. I don't need football to live well. I will live well all of my life.

"What I always say to myself is to enjoy the moment. My present is excellent and I have to continue to enjoy myself. I look at it as projects and the enthusiasm [they bring.]"

Ronaldo helped Juve win Serie A last season, becoming the first player in history to win league titles in England, Spain and in Italy.

"The Juventus project attracted me," Ronaldo said. "It was exciting.

"It was a team that I liked, not only because it's the best team in Italy but it's a combative team that always tried to win the Champions League. I also wanted to win here, like I had done in England and in Spain. I achieved that, something that no player had done."

Ronaldo was recently shortlisted for UEFA Men's Player of the Year award, after also winning the inaugural Nations League with Portugal in the summer.