Manchester United legend Eric Cantona has told Cristiano Ronaldo not to quit Old Trafford, insisting he is already at "the biggest club in the world".
Ronaldo has hinted he wants to join Real Madrid after his part in Wayne Rooney's red card during England's World Cup defeat against Portugal.
Cantona said: "United is the perfect club to improve as a young player.
"United is the biggest club in the world and yet spend time working with young players, giving them a chance."
Real Madrid and Valencia have admitted an interest in Ronaldo, who has said he would like a move to Spain to escape the backlash after appearing to plead for Rooney to be sent off for his challenge on Ricardo Carvalho in the quarter-final in Gelsenkirchen.
"He should keep quiet and do his job"
Valencia president Juan Bautista Soler told his club's website: "It's a utopia, a dream and a challenge to try and bring one of the pearls of world football to Valencia but we are making the first moves.
"It will be very difficult, though."
Cantona is convinced he should stay at United, where young stars get the chance to develop.
He added: "Not many of the great clubs provide this opportunity - in fact, maybe United is the only one.
"For me United is the biggest club in the world and my greatest moments in football were there."
United boss Sir Alex Ferguson has nurtured 21-year-old Ronaldo's talent since signing him from Sporting Lisbon three years ago.
He remains confident the winger will be staying at Old Trafford.
"Cristiano will be coming back," said Ferguson ahead of Tuesday's friendly with the Kaizer Chiefs in Cape Town.
Ronaldo is due to return from his extended three-week break and resume training with Manchester United on 31 July.
Chelsea boss Jose Mourinho, meanwhile, has told his fellow countryman Ronaldo to stay quiet and concentrate on rebuilding his reputation.
He said: "If Ronaldo stays in England I think he can turn things around. Footballers should play a lot and talk very little. He should keep quiet and do his job."