3) Mats Hummels (Borussia Dortmund)
One of the best central defenders in the world, Borussia Dortmund have been reported as accepting a £16m bid from Manchester United for Mats Hummels. The German international, who scored two goals for his country en route to their success at this summer’s World Cup, would be an absolute steal for that price, and a major step forward for United as they look to re-establish themselves as a force of English football.