Former AC Milan defender Paolo Maldini believes that Real Madrid's Sergio Ramos can become the best defender in world football.

However, Maldini has admitted that the Spaniard needs to "work more in his head" to establish himself at the top of the list.

"Sergio Ramos has everything to become the best defender in the world, if he is not already. He is very close, together with Thiago Silva, but he must perfect some things to be the undisputed number one," Maldini told Marca.

"He must be ambitious and work more in his head, because on the physical and technical sides he already has plenty. I am sure that Carlo Ancelotti will be a big help for him in putting the final touches to this.

"He can play in various positions at the back, centre-half and full-back, but to be the best centre-half he must always play a perfect game. Always."

Maldini retired from professional football in 2009.