It was a slip of the tongue, no more, but when Sir Alex Ferguson said that Cristiano Ronaldo is so talented that he is capable of winning the Palme d’Or, suddenly it all made sense. Here was a player in such spectacular form that he was going to bypass the mundane awards that are handed to football players and go straight for first prize at the Cannes Film Festival.

He meant the Ballon d’Or, surely, but as the Manchester United manager once claimed that Roy Keane was so inspirational that he could lead his team to the Boat Race and the Grand National as well as the league championship, maybe he meant it.

Speculation about what Ronaldo can achieve as an individual has increased as his performances in the Barclays Premier League have drawn legitimate comparisons to George Best. These in turn attract rebuttals from men of a certain age, who guard claims to Best’s crown with a ferocity that borders on truculence. Until United lift a European Cup with Ronaldo in El Beatle form, nothing will be good enough, which seems harsh considering the Portugal winger has scored 35 goals for his club this season.

Amazingly, in the circumstances, the jury is out on the player, with the sceptics citing lame performances away to AC Milan in the Champions League and in the FA Cup Final against Chelsea last season as evidence that he is not a player for the big occasion. That could be about to change. If nothing Ronaldo has done in the Premier League is regarded as worthy — and this seems a severe attitude, considering the physical demands of the English game — he has five Champions League matches left this season to prove beyond argument that he is the real thing, starting in Rome this evening and, with luck, ending in the final in Moscow on May 21.

It was the head-to-head in Milan that helped to seal the individual prizes for Kaká last season. As influential in the San Siro as Ronaldo was anonymous, he mopped up the titles of World Player and European Footballer of the Year and understandably so. This season, Ronaldo only needs his defining moment, the performance that will underline his brilliance and confirm the value of what the English public has been witnessing all season.

If Ferguson did not seem affronted by the suggestion that Ronaldo has some distance to travel before his talent is recognised worldwide — and the Italians require some convincing after the damp squib in Milan — this is probably because he is aware of the powerful weapon that is a talented player with a point to prove. Announce that Ronaldo does not have to dominate in Europe to attain greatness and he could lose motivation. So, while endorsing his player completely, Ferguson cleverly left the door open just enough to deliver a challenging reminder of how Ronaldo could silence the cynical beyond retort.

“As for the Palme d’Or,” Ferguson said, meaning Ballon d’Or, awarded to the European Footballer of the Year, “I think Cristiano will have a big chance of winning it, but we will have to get to the Champions League final because if we do it will enhance his opportunity. He hasn’t had as much European football as a lot of the top players and I think his age, 23, is one aspect of why he has not got there yet.

“I think he has matured, though, and in two or three years’ time the questions about his performances in big matches will not be asked. We see development in every department of his game in domestic football and he will eventually show his attributes in Europe. Basically, the more he plays, the more he will display those qualities. I have absolutely no fears about that. I am delighted to be bringing this player to Rome, with his incredible improvement and his goalscoring performances. It is a big advantage for us.”

The idea that Ronaldo has never performed when the pressure is at its most intense does not stack up anyway. In this Champions League season he has scored six goals in seven matches. He was one of the stars of the European Championship in 2004 and guided his country to the 2006 World Cup semi-finals in Germany.

Portugal have made it to Euro 2008, too, with Ronaldo scoring eight times in that campaign. Most significantly, he has refined the style of the modern Manchester United, becoming as important as Eric Cantona was. It is his performances in the past two seasons that have taken this United team to the brink of greatness.

Ronaldo’s genius is his uniqueness, not only the audacious back-heel that opened the scoring against Aston Villa, but his free kicks, struck in an individual way that cannot be imitated or bettered. It seems strange that confirmation of this ability should depend on the odd 90 minutes of football, rather than the weeks and months in which he has been shown to be the best, but just as Colin Montgomerie needed his major and Tim Henman his grand-slam tournament win to be elevated to the elite, so Ronaldo needs a starring role in Europe. Time is on his side, however. He will get it one day; perhaps sooner than many think.