The debate surrounding Cristiano Ronaldo's future intensified last night when Sir Alex Ferguson, the Manchester United manager, claimed that the Portugal forward would be making the biggest mistake of his career if he joined Real Madrid.

Despite Ferguson's insistence - after clear-the-air talks with the player in Lisbon eight days ago - that Ronaldo would not be sold, Real have refused to concede defeat in their attempts to sign him and are said to be considering making an €85million (about £67.5million) offer. But with relations between the clubs at rock bottom, Ferguson launched another broadside by insisting that the Bernabéu would be the wrong environment for a player such as Ronaldo.

Ferguson had previously accused Real of having “no class or morals” in their relentless pursuit of Ronaldo and, given the volatile nature of the Spanish club, the United manager believes that the player should steer clear. “I think he knows genuinely where the best club is to be and that's Manchester United - it's the best one for him,” Ferguson said.

“I have a responsibility for all of my players and their futures are a big concern for a coach. If you are asking for advice and it was your son, you would give him the best advice possible. I believe that could be the worst thing he [Ronaldo] could do - go to Real Madrid. I think, at 23 years of age, he is at the right club.”

Having been told during their summit meeting that he would remain at United, Ronaldo risked incurring the manager's wrath by refusing to confirm whether he would be staying during a televised interview at the weekend, but Ferguson attempted to laugh the matter off yesterday by claiming that it was easy for young players to have their heads turned by the offer of vast riches.

“Young lads can be twisted by the talk of money and the moves that are happening all the time in modern-day football, but if you saw him after the [Champions League] final [in May], he was the happiest boy in the world,” Ferguson said. “The future is, he has signed a five-year contract and has four years left. That is definite. I have seen his signature.”

It is a reflection of Ronaldo's stature that, despite not being on United's pre-season tour to South Africa, talk about him continues to dominate the headlines. But Michael Carrick had some words of advice for his team-mate as the Portugal forward recovers from ankle surgery in the United States.

Carrick, who should be fit to face Orlando Pirates at the ABSA Stadium here this evening after missing United's draw against Kaizer Chiefs in Cape Town on Saturday because of a hamstring strain, believes that it would be foolhardy to leave a team on the brink of greatness. The England midfield player is convinced that United will add to the two Barclays Premier League titles and one Champions League crown they have won in the past two seasons and believes that Ronaldo has a big part to play.

When asked if Ronaldo would be making a mistake by leaving, Carrick said: “Knowing what the club is about, I would say yes. Everything that surrounds the club is moving in the right direction and we want to build on that. The best thing I have done is to come here. For me, it is a no-brainer.

“We drive ourselves on and we expect so much of each other and ourselves. People from outside who have nothing to do with us know what we are capable of and that means more European Cups and championships.”

The Premier League sent letters to United and Liverpool yesterday requesting their observations after Tottenham Hotspur lodged complaints about their respective pursuits of Dimitar Berbatov and Robbie Keane, the forwards. Tottenham claim to have provided the Premier League with a 12-month dossier of evidence supporting their complaint about United over Berbatov.

Wes Brown, the United defender, will fly home tomorrow after the death of his pregnant half-sister, Amanda Fallows, 36, in hospital on Saturday.