UEFA CHAMPIONS LEAGUE QUARTER-FINALS/AS Roma V Manchester Utd:EVER SINCE Cristiano Ronaldo equalled, then obliterated, George Best's record goals tally of 32 in a single season for Manchester United, a debate has raged about who should be recognised as the better player: the guy who grew so tired of beating defenders he found a new way of humiliating them by sitting on the ball, or the boy from Madeira who has taken the art of dribbling to its next level?

For supporters of a certain generation there will always be a strong emotional pull to favour Best, and in Northern Ireland there are still people wearing T-shirts proclaiming "Maradona good, Pele better, George Best". Younger supporters tend to go for Ronaldo on the logic that it is almost impossible to believe there was ever a more devastatingly gifted player in English football.

There is certainly no footballer on the planet playing with more confidence. When Ronaldo scored with a trick shot against Aston Villa at Old Trafford on Saturday it was his 35th goal this season, coming in 37 starts and two substitute appearances. Best's record, set in the 1967-'68 season, was derived from 52 games, which makes Ronaldo's feat even more remarkable.

Ferguson described him yesterday as having a "big chance" of winning the Ballon d'Or and Paul Scholes barely paused for breath when he was asked where the Portuguese ranked in the pantheon of United greats. "I've been very lucky because I've played with a lot of top, top players," he replied, "but Cristiano has to be top."

And yet there is one set of statistics Ronaldo will regard with little affection going into tonight's Champions League quarter-final against Roma. It is the data that reveals he has scored in only two of United's foreign excursions in Europe's premier competition over the past five seasons, and never in the knockout stages. In that time he has been part of 20 away trips and his only goals came in this season's group stage against limited opponents, namely Sporting Lisbon and Dynamo Kiev.

A pattern has developed whereby Ronaldo routinely petrifies the likes of Aston Villa, Everton and Portsmouth but rarely does the same against United's authentic Premier League rivals.

In 29 games against Arsenal, Chelsea and Liverpool he has scored in three. In 11 matches versus Chelsea he has never found the goal.

Last season's FA Cup final was among his poorer performances of the past two seasons. The worst, by some distance, was the second leg of the Champions League semi-final against Milan, when United lost 3-0.

It was certainly revealing to hear Ferguson acknowledge that his player is still acclimatising to the game's highest tier. "He's not had as much European football as a lot of other top players," said the United manager.

"He's only just turned 23, and that's one aspect of it. But I don't think these questions will be asked when he matures in two or three years. We've seen development in every department of his game in domestic football and, eventually, he will show these attributes (in Europe)."

Ronaldo's form is so exhilarating, of course, that taking him to task is not an easy thing to do, and it should not be overlooked that he is currently the Champions League's joint-leading scorer, with six goals in seven games. In a sense, however, the competition starts now, and Ferguson does not dismiss the suggestion that there is room for improvement.

"The more he plays European football, the more he will get used to it and the more we will see his qualities. I have absolutely no fear of it."

Tonight would certainly be a good time for Ronaldo to start dismantling the argument that he finds it difficult to replicate his Old Trafford form in unfamiliar surroundings.

Ferguson spoke of an "incredible improvement" in Ronaldo's performances since then but, as a keen student of United's history, he will also be aware that Best reserved two of his more devastating displays for the European Cup: the 1968 final against Benfica, which United won 4-1, and the 5-1 defeat of the same opposition in Lisbon two years earlier.

Ronaldo was so sublime against Roma last season that the Italian defender Christian Panucci recalls it being the worst night of his career.

"If he starts with the ball you can't catch him," he said. "It's like he's Valentino Rossi. Or Juan Manuel Fangio. If you give me an engine maybe I could keep up with him. Otherwise it's helpless, just helpless."

That, however, was at Old Trafford, and it is time for Ronaldo to start doing it away from Manchester, too. Until that happens, few United fans will believe he is, indeed, better than Best.