Manchester United boss Sir Alex Ferguson wants Rio Ferdinand to prove his fitness this season after only starting 19 Premier League matches in their title-winning campaign last term. The Reds central defensive options have been strengthened with the signing of Phil Jones, to go along with Chris Smalling and Jonny Evans - which all adds pressure on Ferdinand to perform.

"Rio will have to stay fit, that is the key for him," Ferguson is quoted by the Sunday Mirror.

"As he gets older, he won't play all the games because we have Chris Smalling, Jonny Evans and Phil Jones who are the best young centre backs in the country.

"Any one of them can come in."

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