Manchester United boss Sir Alex Ferguson has turned up the heat on Manchester City's record signing Sergio Aguero. City have made the biggest signing of the summer - £38million Sergio Aguero from Atletico Madrid, but Ferguson questions where he will fit in.

and Fergie ­admitted: "He is a good player, of course. It gives them extra up front.

"Their squad is strong and I don't know exactly how they will play him, as they also have Edin Dzeko, David Silva, Mario Balotelli and Carlos Tevez.

"It's a question of who they play with him, or will he play on his own? At Atletico, he always played with Diego Forlan, so it is interesting."

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