SIDELINE CUT:LeBron James has the weight of the world on his shoulders as he tries to save Miami Heat in the NBA finals, writes KEITH DUGGAN

IS THERE a lonelier sportsman on the planet than LeBron James tonight? On Sunday night in Miami, he faces the biggest test of his career. LeBron and the Heat trail the Dallas Mavericks by 3-2 in a best of seven series. They must win their last two games if they are to avoid blowing out in the NBA finals against a team of veterans and one superstar, the model German Dirk Nowitzki, whose public image is one of understatement and old-school skill in comparison to the master-of-the-universe tag that James partly devised and partly had thrust upon him.

But in addition to playing out of his skin in the closing games of what has been an unexpectedly gripping finals series, James must also be wondering how and why he became such a figure of notoriety in American basketball arenas and among the global audience that follow the NBA. The man who tried to follow the path of his idols must be wondering why it is that so many millions of people are fascinated to see if he will fail.

The transformation of LeBron James into a global brand began at the beginning of the century when his high school games in Akron sold out and it was obvious that his freakish combination of athletic power, speed, height and ball skills – although it is his phenomenal power that attracts most hits on YouTube, he carries and passes the ball with the speed and guile of a point guard and in many respects is a team-mate’s dream because his first instinct is to pass – was going to make him one of the most recognisable names and faces in world sport.

And James knew the rules. He knew that persona sold. He developed this pre-game ritual where he would chalk his hands and throw a cloud of dust into the air before a game. Nike got in on the act early and helped to sell the LeBron myth and as a teenager he was drafted by the ailing Cleveland Cavaliers and was instantly hailed not just as a saviour of a mediocre team but as the poster boy for a struggling city. And in his six years there James leapfrogged his way up the scoring charts and did everything that was expected of him – except lead Cleveland to an NBA championship.

The 2010 play-offs was the nadir of his basketball life, when he was booed in his home court by fans distraught after his miserable fourth-quarter showing against the Boston Celtics. And it might have been that experience that prompted him not to re-sign with Cleveland but to think about joining other clubs, a choice that was televised live in a daft moment of hubris and naivety named The Decision and culminated in James making the statement that has become a metaphor for sporting vanity and egotism: “I have decided to take my talents to South Beach.”

Had James decided to remain in Cleveland, thereby chaining himself to the unfashionable city of his home state for better or for worse, his loyalty would have been beyond criticism regardless of how things went on the basketball court. Had he decided to go to the New York Knicks, still the most regal team in the NBA stable despite a lack of championships that dates back to 1973, then he would have been joining a team and a city that could match him for ego and ambition.

But instead he chose Miami, the city, as Lenny Bruce said, where neon goes to die. The Miami Heat aren’t even as old as LeBron, formed in 1988 as part of the NBA’s aggressive policy to create teams wherever they felt there was wealth and an audience. The arrival of LeBron brought about a partnership with Dwayne Wade, the haughty and brilliantly explosive guard whose pomposity seems to know no limits and who, with big man Chris Bosh was meant to make the Heat unstoppable.

And that is how it was panning out until earlier this week when Miami faltered in their last two games in Dallas, with James virtually anonymous in the fourth quarter on Thursday night, scoring just one basket in the last 30 seconds with the game already over. So now King James, as he was dubbed in his school years, is once again hearing the old accusations that he cannot cope with the pressure coming at him more loudly than ever.

James is unarguably one of the most extravagantly gifted basketball players to ever play the game. He played a storming role when his team defeated the Celtics earlier in the play-offs and afterwards spoke so eloquently and respectfully about the beaten side that it seemed as if he was ready to say and do the right things and do what the basketball world demands of him: win championships.

And that is what has made these NBA finals fascinating. You can bet that most of Germany will be staying up late tomorrow night to see if Nowitzki, the seven-foot shooting machine who went from second division Bundesliga to the pinnacle of the NBA, can win his first championship. But the story behind the story boils down to the possibility that LeBron is going to blow it.

And all of this has only happened over the past two games. Just a few days ago, ESPN’s columnist Rick Reilly was predicting “Eventually, LeBron James is going to win enough rings to open a pawn shop.” Maybe he will but that is not looking like such a good presumption just now.

Next year will be James’s ninth season in the league. James entered basketball with much the same hoopla as Tiger Woods entered professional golf but Woods won his first Masters in his first year as a pro and then dazzled and subdued his supporting cast in the decade that followed. James has spent what is threatening to become an indecently long time actually delivering on his extravagant brilliance.

And that is why tomorrow night’s game back in Miami promises to rank with Barcelona’s performance in the Champions League final as one of the best evenings of sporting theatre of the year. Since James joined the Heat, they have become the most hated team in the NBA, regularly booed on their away games. But the single most irritating thing about them is that for home games in Miami, the arena only fills up after the game has begun, creating the notion that the beautiful people were too busy with their glamorous lives to bother showing up for the appointed tip-off time.

That was never a problem in Cleveland, where James commanded full houses through his six years, where James was a folk hero rather than just another diversion in a playground of the rich. His “abandonment” of the ultimate blue-collar city for somewhere as craven as Miami had practical consequences: James draw was worth an estimated $48 million (€33.5m) per year to local businesses and his absence cost money.

None of this, of course, is James’s fault. He is just a young man with a preposterous gift for sport who is trying to figure out who he is and how he should behave day in and day out. He has occasionally said stupid things and tends to showboat and is never going to be a folk hero.

But it is no longer about how he behaves or about his exalted gifts. It comes down to whether he can apply them now that the NBA finals have reached the crucial point and James, like the rare cast of greats with whom he has been compared, is expected to own the night.

So back to the steamy city, then, to find out if James has the coldness needed to take over the minutes that matter and leave his mark on them. The chances are that Miami’s glittering set will show up on time for this one.