The 21-year-old still has six years left on his current deal.
He told Radio Marca: “The idea has always been the same. That’s why I signed such a long contract.
“What happens is that nobody in football has guaranteed place anywhere. Today everything is so changeable, so complicated that you never know, but the truth is that I’m very happy, very motivated and being captain is an extra incentive.
“Everybody knows that one day I would return to Spanish football. It’s an experience I want to live. I want to play in Spain as a professional.”