El Mundo Deportivo says the English club has contacted the 18 year-old Mexican's agents in recent days to inform them that they're ready to pay Dos Santos' £20 million buyout clause.

A source close to the Dos Santos camp said: "Barca has committed an understandable, but dangerous, error. They've allowed the world to see this diamond without guaranteeing that there is no chance of him being snatched away."

Dos Santos now carries a Spanish passport and he is hugely admired by Chelsea boss Jose Mourinho and Liverpool's Rafa Benitez.