As a rule, anyone as warm, personable and natural as Novak Djokovic could be marked down as a good, talented fellow who probably would not make it to the top. He loves to have a party, to sing, to muck around, to impersonate the mannerisms and service actions of the other players, especially the best and most serious. Just past 20, and the youngest man left in the Wimbledon singles, there is still something of the puppy in him. He applauds his opponents’ best shots and hugs them at the end of matches, win or lose.

Djokovic has a huge appetite for life, but a sense, too, of its absurdity. With his jet-black brush of hair and erect gait, he has a comic air about him. And despite his rapid rise to the rank of No 5 in the world, he has no pretensions, which is most unusual in his profession. He is fiercely loyal to his country, Serbia, and to his family.

Recently, when Djokovic was driving in Belgrade, the city of his birth, he stopped at a traffic light and was approached by a group of gypsies begging for money. What would you have done? Djokovic paid them all. “There were four of them and each had his own role,” Djokovic said. “They did it so good I had to pay each member.”

But to conclude that the amiable Djokovic has a soft centre in his tennis, or a less than wholly competitive attitude, or that he might lack the killer instinct, would be to get him wrong. There are two sides to the 20-year-old Serbian. One is the good guy. The other is the driven sportsman whose ambition is to be nothing less than the best. About that, he is always serious.

Until the turn of the year, Djokovic was recognised as a player of the future, one of the few, including Andy Murray, forming a preliminary queue to seriously challenge, even one day take over from, Roger Federer and Rafael Nadal. At the end of the 2006 season, Djokovic was ranked 16th. Murray, who was born a week earlier than Djokovic in May 1987, was 17th.

After that, Murray moved briefly ahead but Djokovic has since stolen a march and made credible his aspirations. In the spring, he played what he calls “the tournament of my life” and the “match of my life”. The tournament was the ATP Masters event in Miami, just about the most prestigious tournament outside the Grand Slam championships, and he won it without dropping a set. The match was his defeat of Nadal, 6-3 6-4. Along the way, he emphasised the gap he has opened on Murray by beating him 6-1 6-0. “I’ve always tried to compare myself to the best players in the world, because that’s what I want to be one day,” Djokovic said after lifting the trophy.

“Right now, I feel for the first time that I deserve to be one of the three best in the world. I think I have proved that with the win over Nadal.”

He knows what it takes to go further. “Practice, practice,” he said after losing to Nadal two weeks earlier. “Tennis has changed a lot in the past 15 or 20 years. The players have to work more and more, the points are longer and you’re playing under heat. I’m not the kind of guy who is going to just rely on his talent. I know I need to work and I know what I need to improve.”

He is also happy to invest his burgeoning earnings. As well as a full-time coach and fitness trainer, Djokovic employs Mark Woodforde, the winner of six Wimbledon doubles titles, chiefly to improve his volleying. “I’m part of his project,” Woodforde said. “I can see why he’s in the top five now and he will improve. It’s a pleasure to work with someone who sets such high standards for himself. He has a fine serve, backhand and forehand, terrific speed and a big heart. He’s smart and he learns something every time he loses and unlike some players, he embraces publicity.”

When Djokivic finished the 2006 season inside the top 20 of the rankings, his father, Srdjan, congratulated him, only to be corrected. “It doesn’t matter if I’m No 27 or 87,” Djokovic said. “When I become No 1, then you can congratulate me.”

There’s no doubt who is doing the driving and it’s not the parents. For many years, they have run a pizza and pancake restaurant in a mountain resort near Belgrade. Djokovic’s father was a professional skier and a good footballer. He hoped his son would choose one of those sports. But when a tennis court was constructed across the road from the restaurant, four-year-old Novak asked for a racket and never looked back.

“He gave us the highest goals, and we run behind him to give him what he needs,” his mother, Dijana, told an interviewer in Paris while her son reached the semi-finals of the French Open, falling without disgrace to Nadal.

It was Djokovic’s parents who permitted him to leave home two months before his 13th birthday, when he went to the tennis academy near Munich owned and run by Niki Pilic, who served for 16 years as Germany’s Davis Cup captain.

Pilic, a Croatian, and his Serbian wife, charged a special rate and took care of Djokovic, who did not go home for two years for he was young, very talented, and his parents were not wealthy.

“He was very bright, and he hit the ball very well but what marked him out was that even at that age he knew exactly what he wanted to achieve,” Pilic said.

“I remember going out to warm up with him one day, and he took me to one side and said ‘I don’t want to waste my career’.

“He still has that focus today. But back then it was clear that he had a lot of character and an intelligence for tennis.” Djokovic’s greatest weapon, according to Pilic, is not the much-lauded backhand down the line or the forehand, or even his blinding speed, but his “mental stability”.

His two younger brothers, Marko and Djordje, also train at Pilic’s academy.

Marko is the Serbian under-16 champion, and Djordje, 12, has the same talent and will to succeed that marked out his eldest brother, as well as the same smile and hairstyle. “People beware,” Novak Djokovic wrote in his latest message to fans on his website. “The train with the Djokovic family is arriving at very fast speed and it has no intention of stopping.”

A dynasty is unlikely, but the upward journey of the remarkable Novak Djokovic, the best young player in the world, will be well worth watching.