SIDELINE CUT/Keith Duggan: They say that if you are good enough, you are old enough. The aphorism rings particularly true when you consider the American sports scene at the moment.

Today, 14-year-old Freddy Adu will make his Major League Soccer debut for the Washington club DC United.

The Adu family resisted the overtures of the corporate cheque books and the earnest entreaties of European giants like AC Milan all through Freddy's 13th year, but last November they caved in and their son signed for the MLS, his $500,000 making him the richest contract holder in the league.

The obligatory $1-million Nike endorsement quickly followed and sometime today, against the splendidly named San Antonio Earthquake, Adu will become the youngest American in over a century to play in a professional sporting encounter.

Where adolescent sporting sensations were once the province of lonely hothouse sports like swimming, gymnastics and tennis, the phenomenon of the man-child is radically altering the age profile of the big-ball sports. Just under a year ago, high-school marvel Le Bron James became the most hyped basketball player ever to enter the NBA - the hullabaloo that followed the ascension of Jordan and Magic Johnson was quaint by comparison - and already James, at 18 years of age, is that league's brightest asset.

The MLS are predicting Adu's presence could be enough to trigger the soccer revolution in a country that failed to be wowed by the delights of Best and Pele in the 1970s. But those icons came to America to bask in the afterglow of their own comet shoot across the beautiful game.

Adu is to soccer what the nascent Bobby Fischer was to chess - except that Adu is technically still a kid. A profile on Sixty Minutes, innumerable magazine shoots and instant elevation to the top of the soccer money heap make Adu "Da Man" in the eyes of most Americans, even though he still probably sneaks a peek at his favourite cartoons. But unlike Fischer and the vacant-eyed princesses of yesteryear's tennis circuit, Adu seems gloriously prepared for the meltdown of professional sport. Although born in Ghana, he recently received US citizenship and his stated aim is to play in the World Cup final with the USA.

It is anticipated his first major tournament will be at Germany 2006, when he will be a battle-scarred veteran of the MLS and 17 years of age, the same as Pele was when he presaged his breathtaking gifts at the World Cup in Sweden in 1958.

And even as the world golf gears up for the US Masters in Augusta, Michelle Wie, born in Hawaii the same year as Adu was born (1989), continues to make disquieting progress. Although still an amateur, she took part in last week's Ladies PGA tour event at Dinah Shore and finished fourth.

Just 14 and almost six feet tall, Wie is already driving the ball over 300 yards, something that seems not yet to have fully registered with the golfing fraternity. Her power is unimaginable and, carefully cottoned by her parents, Korean nationals who met in Hawaii, Wie has the benefit of an apparently happy and secure background.

Last year, Fred Couples described the sight of Wie driving as "the scariest thing you have ever seen". Wie's stated ambition is to play in the Masters, a dream that may seem less and less unlikely over the coming couple of seasons. It is almost certain she will apply to the LPGA for full membership before the standard age of 18. But the real intrigue lies in her potential to break through the glass ceiling that did not even crack when Annika Sorenstam threw her best stone. Still a kid, Wie has the physique and the fundamentals to make her a viable candidate for the men's field. And like Adu, she is uncommonly adept in dealing with the attention her unprecedented aptitude for the game has provoked.

Tiger Woods was little more than a rumour waiting to happen in terms of international exposure prior to the 1997 Masters, when Peter Alliss's murmured refrain was, "He's not yet 21, you know."

Because the 1996 tournament featured a melodramatic home nine between Nick Faldo and Greg Norman, two pillars of the modern game, Woods's calm assumption of the leaderboard the following April unnerved many. It was not so much a golf Major as a coronation and, because of his youth, it was predicted Woods could dominate golf to the point of ruining it.

That has not happened but Wie has adjusted the age barrier even further in a sport where the top players used to peak in their 30s and 40s. How Wie might reshape the appeal of professional golf is beyond prediction: the experts have nobody to compare her to. But already, she is emulating Woods in further reclaiming the sports from its stereotypical masters - white, middle-aged, wealthy males - the very types that will run this year's tournament in Augusta. And like Woods, she stands to become a very wealthy young person through golf.

In comparison to Wie and Adu, Everton's "teenage wonder" Wayne Rooney suddenly seems ancient. As for Martina Hingis ending her tennis career at 20, about time for her. And Zinedane Zidane may be the finest soccer player on earth, but perhaps the sight of him running around arenas with a great, shining, bald patch suddenly looks a touch undignified.

There are a million reasons why people are uneasy at the prospect of a generation of Shirley Temples in Nikes bursting from the wings onto the merciless stage of professional sport. Childhood is the obvious casualty. History is littered with examples of prodigies that sparkled for a season but quickly wound up spent and unhappy and forgotten. But equally, sport has left many more individuals that progressed through more conventional channels in an equally wretched state. Think of the car wreck Paul Gascoigne's life has become.

Temperament is the key. If a teenager like Adu possesses a talent that is literally irrepressible, is it right to delay him from expressing it in a compatible environment? What young club apprentice wintering diligently in digs and scraping through the youth system in England would not swap places with Adu right now?

The reality is that childhood is the time when prospective athletes with ambitions to make a livelihood from their talent start thinking and behaving professionally. Fame is the spur. And money. Adu and Wie are coping with the perils of both with a level of grace and maturity that shames the example given by so many of the supposedly adult stars in the NFL, the NBA, baseball and English soccer - and across the spectrum of big time sport.

Adu and Wie are unaffected, articulate, level-headed and joyfully unrestrained in their ambitions.

Let us hope they remain untainted by the prevailing traits that seem to afflict so many adult sports personalities - preciousness, impetuosity, arrogance, irresponsibility and vanity. If it takes the kids to wise up the field, then throw them in there.