If he wasn't the world's greatest tennis player, you'd think he was royalty, or Bono, or a diplomat at least. Fluent in four languages, and a world traveller since the age of 14, he immediately grasps the essence of Japanese culture, which bewilders most foreigners on their first visit. He talks about the 'respectful heart' of Japanese tea ceremony, the 'meticulous and harmonious' people, the 'quiet and relaxed' streets of Tokyo, and a samurai named Benke. He's on tour more than Kofi Annan, and spends more time in Asia than the United States or his native Switzerland. His secret weapon is training in 45-degree heat in Dubai, which makes events in New York or Melbourne seem air-conditioned. Asked at a party how he liked being a diplomat, he said with a friendly manner: 'Yah, you've gotta be.' Actually, Roger Federer is a diplomat, this year named the Unicef ambassador for children, in recognition of his charity work for the disadvantaged in South Africa. Though not officially royalty, his first match in Japan was a game of doubles with Crown Prince Naruhito on a clay court inside the palace. At age 25, Federer's off-court persona seems saintly compared to other all-time greats like Ruth, Ali, Jordan, Gretzky and Bonds, who were dogged by allegations of one kind or another. While Maradona used the Hand of God, Federer appears to have the mind of a deity. A vegetarian until recently, he seems more of a Zen philosopher than a party animal. After drinking sake and walking in his sleep at a Tokyo hotel room into a bedpost that cut his shin, he wrote this on his blog: 'Apparently there was a famous Japanese samurai called Benke who killed a lot of warriors during his battles. They say that his downfall was a weakness in his shin.' How many sportsman write about Japanese history? 'I don't think there's ever been a number one who gets along with everybody and has no enemies,' says his agent, Tony Godsick of IMG. 'It's very rare. You wonder sometimes if tennis realises what they have right now.' Asia's greatest players, at least, realise what they have. They say that Federer's humility and dutiful demeanour, which make him appear too boring for western celebrity, give him an appeal in the Orient that transcends his sport. 'Japanese like him because he's really quiet. He doesn't perform too much, he's really smooth,' says Ai Sugiyama, Japan's best female player. She agreed that he was a sobokuna ningen - a pure and ordinary guy, like baseball stars Hideki Matsui and Ichiro Suzuki. 'He can accept things really well. He never gets panicked. He has an aura.' Paradorn Srichaphan, Asia's top-ranked male player, says Federer has the self-control of Buddhist monks who taught the Thai about meditation at temples. 'This is his greatest weapon. He controls the match by showing his calm. It drives the opponents crazy because you can't do anything to make him lose control.' He's almost humble to a fault; make that a double fault. Called the greatest player ever by many of his peers, he says he 'got lucky' to beat 1,078-ranked Japanese player Takao Suzuki last week on his way to winning the Japan Open. During the tournament, he didn't publicly complain about jet lag, a typhoon, limited practice time, early matches or endless fans yelling at him 'Roja, sign please!' Federer said his goal in Japan was to 'entertain not only myself but the whole city and country'. His first practice was on centre court, with acid jazz music, ball boys, an unranked Japanese player, no umpire and about a thousand fans clapping after points. Later, he answered, without cynicism, translated questions such as 'how do you make topspin' and 'is your goal to win'? At a pre-tournament gala packed with Japanese socialites, paparazzi shouted: 'Left-o! Right-o' to position him for photos as if he was another foreign model at a corporate promotion. Instead of griping, he mocks himself and the situation. 'You see, I'm very flexible,' he says. Wearing a Dolce & Gabbana suit, he asks self-consciously: 'Do you like it? Or not?' While handlers waited to whisk him off stage, he remained to talk about his interest in poverty and world peace. 'I'd like to put more time into that. I can use my on-court creativity off the court as well,' he said. 'Hopefully I've got another five or 10 years ahead of me in tennis. But later, I'll definitely do more for the Roger Federer Foundation and Unicef.' While tennis legends Jimmy Connors and John McEnroe have dabbled in coaching or broadcasting, Federer seems destined for a role on the global political stage. 'Off the court he realises he can have an impact in different areas with his charity work and other things,' says Tim Henman, Federer's best friend on tour. 'He realises there's a life away from tennis and he doesn't let that distract him. It's one of the reasons why he's so good on the court. He's able to relax and switch off to different things.' Federer says his diplomacy comes naturally from being a world traveller since age 14. 'Discovering the food and the culture is very important to me.' Like Bono, who married his high school sweetheart and plays in a band of Irish schoolmates, Federer has the spiritual backing of a circle of family, lifelong friends and the same soul-mate, Mirka Vavrinec, since he was 19. 'My parents raised me very well,' he says. 'I've had good coaching and good people around me my entire life. I've been with my girlfriend for six years, so that kind of grounding has been very helpful.' He admits he isn't always comfortable in the off-court spotlight. 'Being on the red carpet was quite difficult in the beginning,' he conceded after winning crystal-maker Baccarat's Athlete of the Year award. 'I'd get really nervous. I couldn't get comfortable. But now I'm getting much more comfortable talking in a suit, whereas before I was in a track suit. It's a totally different life, like day and night. I'm happy that I've been able to make the transition.' The agent Godsick says Federer has a rare gift for making a broad spectrum of people feel good about themselves. 'He feels somewhat guilty that he picked up a racquet, played with his friends and now he's successful. That's why he wants to give something back. Nobody approached him about the charity in South Africa. He did that himself.' Godsick adds that there's never been a number one who's played such a global schedule. 'Some players need to get back to America or their home countries quickly after the event. Roger's not like that. He does press conferences in four languages, and doesn't feel it's a burden to him. He really wants to grow tennis globally.' Next month, he is set to play the ATP Masters in Shanghai and an exhibition against nemesis Rafael Nadal in South Korea. He said he would love to return to the Japan Open, which attracted 70,000 fans, a third more than last year. 'I had a lovely time here,' he said after beating Henman 6-3, 6-3 in the final. 'It was 10 times better than expected.' After his final presser, about 200 Japanese fans waited in a corridor with programmes, balls, and racquets to sign. Federer could have ignored them, as other champions did. But he took the time to autograph each one. He then clapped for them, and bid them sayonara with a very Japanese bow worthy of the doubles partner of the Crown Prince.