Novak Djokovic is one of the great tennis players of our time. He has won ten majors, became the only man to ever defeated clay king Rafael Nadal in straight sets at Roland Garros, and has been world number one for over a year. He is an unbreakable machine, with the best return in the game, the best defence in the game and a relentless, ruthless accuracy. In the 2011 US Open semi-final, the great Roger Federer had two match points on his own serve, yet he could not put Djokovic away. The Serb held firm and won the match – the man is nigh on impossible to beat.

You might expect, then, for him to be adored as much as Federer and Nadal, the men he supplanted on his rise to the top. If Federer is beatified like a Messi figure, and Rafa’s power and fitness praised like Ronaldo, then surely this modest man, who has beaten the other two so many times in recent years, deserves the same treatment? Yet when he defeated Federer at the Swiss’s second home – the Arthur Ashe stadium, where tennis’s golden boy has won five times – he was greeted not with elation but with disdain. The crowd had made clear their favourite – every Federer winner was greeted as a match winner, while Djokovic faced boos and disruption. They even celebrated a fault in the final game. Rewind a few months to Wimbledon, with Djokovic again facing Federer, and you find the same phenomenon. How can we explain it?

It is not as if Djokovic is dislikeable. After the match he maintained his usual politeness, refusing to blame the crowd and humbling himself by declaring that he would try to “earn their support” – as if his wondrous feats aren’t enough. He speaks English as perfectly as Roger, and doesn’t take himself too seriously. He’s a joker: someone who once took a golf club to his opening match at the snobbish Wimbledon. And he’s a nice guy, once handing out free chocolates to journalists at an end-of-season press conference.

No, the answer has deeper, more unsavoury roots. In fact, the answer lies with tennis’s class problem. Tennis is not a sport for your average citizen – centre court tickets at Wimbledon regularly exceed £100, and Wimbledon has been described as a “sub-Ascot”. When you think about the strawberries and cream, strict player dress code and almost universally posh voices, it’s hard to disagree. The same is true of the Aegon Championships, held at the fancy west London Queen’s club in June, where you find yourself surrounded by the monied elite. Investment bankers, lawyers, hedge fund managers, and more. Sure, this is one extreme, but it’s indicative of tennis’s profile.

The rich have always decided what constitutes art, from Renaissance paintings to modern theatre critics. Roger Federer is nothing if not middle-class sporting art – fans often wax lyrical about how the man “oozes class”. From his elegant backhand to his RF branding, from the cardigans to the coiffed hair, the 17-time Grand Slam champion embodies the middle-classes and their love of the artistry in sport. His seemingly effortless of his strokes chimes with middle-class entitlement. For them, it’s almost distasteful to watch a player, male or female, stretch themselves, push themselves. The sheer physicality of Nadal, Djokovic and Murray is off-putting, because it shows people struggling for their dues, as they’ve never had to.

Rugby is brutal. Football is foul-mouthed. Even handball has its physical moments (see p.39). Yet in tennis you can still find the word decorum. You see it, for example, in the pleasure commentators and pundits took in knocking tennis’s abrasive bad boy, Nick Kyrgios, down a peg or two. And you most definitely find it in the attitude of the tennis community towards its top players. In the women’s game, Serena Williams is denied the adulation that should come with her all-conquering achievements. One explanation might be that deep down, tennis would prefer Maria Sharapova, with her long blonde hair and tall thin body better suited to white Western models of femininity than the muscular American. Williams’ style too – flat strokes, loud emotive grunts – has certainly played a part in her never truly being embraced. The same is true of Djokovic, Murray and to a lesser extent Nadal. Both the Serb and the Scot get visibly angry with themselves on court, shouting and screaming. This isn’t acceptable according to the middle-class dogma of the stiff upper lip, the idea that displaying emotions is distasteful; a norm which Federer follows impeccably.

Tennis cannot keep on like this forever. Djokovic is no aberration – rather, he embodies the new trend of scientific sports, using ice baths, following meticulous diets, training relentlessly. As sport continues to become more meticulously professional, science is playing an ever greater role and physicality is becoming more important. You don’t see the Paul Gascoignes anymore; rather, supermen like Cristiano Ronaldo. Sport is gravitating towards the Djokovics, not the Federers.

The nature of tennis support is changing, too. Crowds will not stay impeccably silent forever – as the players become branded superhuman sporting machines, their global support will rise, and the urge to cheer them on will become stronger. The old golf-style model of silence followed by polite applause might not cut it anymore. Unless tennis finds a new way, might its decorum be on the way out?

While the sport itself remains safe, the decorous model of its sporting profile is under threat. Its replacement, funnily enough, already exists in the Davis Cup. Tennis’s global competition – actually the world’s largest annual team tournament – has never garnered as much support as football, rugby or even cricket in the world cup stakes. Its status is less exalted, and because it is so time-consuming it often loses star players – neither Federer nor Wawrinka are playing this year. Yet it provides a new model for tennis. Going to the Great Britain versus France tie, I was reminded more of a football match than the respectful silence of Wimbledon. With an invested, partisan crowd, the atmosphere is electric. Each point is like a penalty shoot-out. The dress sense is eccentric. This is community.

It’s also a musical affair. Here the end-of-season ATP World Tour Finals provide a template. Booming music during the breaks and interactive screens: this feels more like a nightclub than Wimbledon. But it represents the future, and one that the Davis Cup has already embraced.

Moreover, the Davis Cup demonstrates the benefits of attracting a less monied audience. It may be a cliché that gentrification leads to the demise of an ‘authentic’ atmosphere (the Cereal Killer Café is the prime example), but it contains more than an element of truth. When Team GB played in Glasgow, the atmosphere was incredible, and spurred them on to victory. By contrast, at the Queen’s Club, an appeal from Team GB was needed for the crowd to get involved, and members were even sent an email after the first day asking them to be a bit more ‘patriotic’ in their support. Even then the massively outnumbered French contingent was more than a match for the crowd. Tennis could do with a more diverse following.

The old era of lofty posturing and respect for the artistry of sport is over. Today, players are becoming less like gods, and more like supermen. Tennis needs to change with them.