Cristiano Ronaldo will be allowed to leave for Real Madrid for £75m

Manchester United will sell Cristiano Ronaldo - if Real Madrid president Florentino Perez comes up with a stunning £75million.

Boss Sir Alex Ferguson and the club's money men believe this is the magic number that would make the move happen and are prepared for an official offer in the next few days.

United won't sell Ronaldo for anything less than a top price, but they accept business could be done if Perez can back up his dream with cash. Perez publicly announced in Spain yesterday that Ronaldo is his next target, to play alongside Kaka.

But in Italy, angry Milan fans protested about the impending sale of their star man. Convinced he will be able to trumpet the world record £60m capture of Kaka from AC Milan by Monday, Perez put Manchester United back on a war footing as he once again courted Old Trafford's Portuguese ace.

"Kaka, Cristiano Ronaldo and Lionel Messi are the best players in the world," said Perez.

"Now I'm going to work to bring Kaka and Cristiano Ronaldo to Real Madrid."

Ferguson knows a £75m fee is good value and it would give him the funds to sign two or three players. United have not raised the subject with Ronaldo, who has been on holiday before joining the Portugal squad for their World Cup qualifier away to Albania.

However, Ferguson has told friends in the game that £75m is the level that would make United take Real seriously and see the Reds star head for Spain.

United have stepped up their interest in Luis Antonio Valencia at Wigan. Ferguson was willing to let striker Fraizer Campbell go to Wigan as part of the move, but a £17m cash offer may close the transfer.

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