Cristiano Ronaldo has not ruled out leaving Real Madrid before the end of his contract, telling German football magazine kicker: "You have to do whatever makes you happy."
Ronaldo, 30, signed a new five-year contract in 2013 but he has been the subject of persistent rumours linking him with Paris Saint-Germain, Manchester United and Major League Soccer.
PSG captain Thiago Silva recently said he hoped the French champions would reach a deal to sign the Portugal international in 2016, while Ronaldo's close friend Jose Semedo has said the forward wants to end his career in England.
Former Manchester United defender Patrice Evra even claimed that Ronaldo had been close to a return to Old Trafford two years ago, and Ronaldo has suggested he could imagine leaving the Bernabeu before 2018, asking: "Why not?"
He added: "Right now, I play for Real Madrid, but you never know. You have to do whatever makes you happy. You never know what happens tomorrow. I can only say that I will always give it my all for my club and my country."
Ronaldo, a three-time Ballon d'Or winner, also said that he was not worried if pundits felt that Barcelona stars Lionel Messi and Andres Iniesta were superior.
"I am happy and proud about my career," said Ronaldo, who was speaking to kicker to promote his upcoming film. "Maybe you think that Messi is the best, others might go for Iniesta.
"I respect that, but to me, I am the best."
He added that striving to become the best in his profession has been "the reason that I have improved that much in my career, and that I have achieved that much."
Ronaldo said no other player could match his consistency since 2007.
He said: "I've been the same for the last eight years. I have always played at the highest level. Name one player in the history of football who has achieved that in eight consecutive years.
"Whoever picks up the personal accolades or who wins the league or the Champions League? That's down to the little details."
Asked about his greatest weakness, he replied: "I've got many, just like all of us. After defeats I am certainly too angry. That's my manner, and those who know me will let me get away with it."
He also said that the constant whistling and booing he faces from rival supporters fires him up.
"In a certain way, I also like that," he said. "It fires me up when the people whistle and shout, for instance during away matches. You always have to see the positive side of things."