Casemiro Real Madrid trump card in battle for Porto star Danilo

Casemiro is Real Madrid's trump card in their transfer battle for Porto fullback Danilo.

Danilo is also interesting Manchester United, Liverpool and Barcelona.

However, Casemiro, on-loan at Porto from Real, has been talking up life in Madrid to his teammate.

Marca says the pair have become good friends and Casemiro is urging Danilo to choose Real, should he decide to leave Porto this summer.

"If you leave Porto, you have to go to the best club in the world," declared Casemiro.