8. Cristiano Ronaldo

Why isn't Cristiano Ronaldo higher on this list, I hear you cry.

Well, remember that the Portuguese superstar turns 30 in less than a years' time - and then consider that fact that he is indispensable to Real Madrid, who handed him a new long-term contract last September.

Even if he doesn't stay at the Bernabeu until 2018, no club will be prepared to pay more than £86m for a player in their early thirties.

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