Carlo Ancelotti spoke to the media ahead of Real Madrid's match against Sevilla about a percieved attitude problem in the squad. (1:08)

Real Madrid forward Cristiano Ronaldo has a one billion pound ($1.51B) release clause in his contract, according to his agent Jorge Mendes, who told the BBC that the Portuguese star would sell for 300 million pounds if the club decided to let him leave tomorrow.

Mendes said he believes Ronaldo will see out his career with the Galacticos and said that the 29-year-old was the best player and sportsman ever.

"Cristano Ronaldo? One billion," Mendes said when asked by the BBC how much the three-time Ballon d'Or winner was worth. "His buyout clause one billion, so it is one billion. If, for any reason, the club decide to sell him tomorrow for 300 million, someone will pay.

"He loves the Manchester United supporters because he was there six years but he will finish his career at Real Madrid, for sure," said the Portuguese agent, who began his career as a nightclub owner in Porto and who has reportedly taken charge of transfers worth more than one billion pounds in total.