Rafa: My Story
Rafael Nadal with John Carlin
Sphere, 272pp, £17.99

Golden ages are usually tricks of history, myths born of nostalgia. In the case of men's tennis, the golden age is very real and it is happening now. Just when you think that the sport can't get any better - that human beings cannot strike and retrieve tennis balls with any greater skill and athleticism - another tournament sets the bar even higher. The rivalry between Rafael Nadal and Roger Federer was breathtaking; now Novak Djokovic beats them both. Tennis is evolving at breakneck speed.

Here is the surprising twist: 25 years ago, it was assumed that John McEnroe-style outbursts would become the norm. The opposite has happened. Federer and Nadal have proved champions in every sense of the word - gracious, articulate and respectful. Rafa: My Story, John Carlin's rendering of Nadal's autobiography, is not just a study of one champion; it examines the rivalries that have made men's tennis the most admired sport in the world.

Nadal is always scrupulously courteous about Federer, so much so, that some cynics wonder whether this is just for the cameras. That scepticism is almost certainly misplaced. There is not even a hint in this book that Nadal is pretending to admire his rival. Quite the reverse. "His physique - his DNA - seems perfectly adapted to tennis," he says of Federer. "You get these blessed freaks of nature in other sports, too." If anything, the subliminal message is that Nadal is still slightly in awe of the man he has beaten 17 times out of 25.

Explaining that paradox takes us to the heart of the rivalry. Nadal is relentlessly spartan, pursuing perfection of a monastic purity, driven by self-denial. He never misses a training session, never allows himself to admire his performance. It is a life more admirable than enviable. This desire to please is part of Nadal's boyish charm, as though he hasn't quite flown the nest. And he hasn't. He still lives in the house where he grew up in Majorca; his mother still packs his bags for major tournaments. On court, he is arguably the toughest competitor in world sport; off it, he is a bundle of anxiety, scared of animals and even the dark. Carlin's term for this split personality is "Clark Kent" - by an act of psychological alchemy, Nadal converts all his insecurity off the court into a controlling spirit on it.

He plays as though he couldn't bear to let anyone down. But what about him? Does he enjoy tennis? He inevitably draws satisfaction from his achievements and is astonishingly resilient. But does he enjoy it on court, as he chases down another lost cause, retrieving the impossible ball, pushing body and mind to the limit? Could anyone enjoy playing that way?

You get the impression that Nadal plays as much out of duty as for the love of it. He is the visible part of a collective effort, a family's shared endeavour. When his godmother congratulated Rafa, Toni (his uncle and coach) remonstrated with her: "What are you doing?" Toni's logic was that it was like congratulating herself. "If one of us wins, we all win."

Nadal is driven by that familial obligation. He made a choice to become a tennis player and, having done so, he owes it to everyone who has helped him to give of his best, every day, every point. It is here that the contrast with Federer is most marked. Federer plays with joy, with barely constrained amazement at his own mastery. He is sport's ultimate aristocrat. His manner implies a rare self-belief and suggests he might be thinking: "The world may give out its prizes as it wishes (and incidentally, I have most of them), but that is immaterial, compared to the joy I get from hitting tennis balls so elegantly, so perfectly." If happiness is finding the right medium to express your innate talents, then the Swiss champion must be one of the happiest men in the world.

Nadal acknowledges his great rival's easy calm and perhaps he subliminally envies it. Even though he has beaten Federer so many times, that doesn't obscure that Nadal sees in him an unrestrained expressiveness and openness that he finds more elusive. He has trained himself to be the ultimate winner, but the real nature of winning is much more complicated than what is written on the score sheet.

Nadal has always played with a hounded intensity, as if he were scared of someone noticing that he'd taken his foot off the gas. That someone is Uncle Toni. Nadal's parents in effect ceded control of the tennis-playing strand of their son's character to Toni, his father's brother. Given that Rafa was obsessed with tennis, that strand was a large facet of the boy's personality.

Toni was brutally tough with the future champion. Nadal's godfather argued that what Toni was doing to the child amounted to "mental cruelty". Yet whereas Andre Agassi couldn't escape from his tennis-obsessed father, Nadal's parents provided more than enough warmth and affection to balance Toni's toughness. Even now that he is a global icon and ten-time Grand Slam winner, his uncle will intervene in apparently mundane matters. When they are going for dinner at a restaurant that requires formal trousers, Toni tells Rafa to go back to his room and change out of his shorts. Rafa would have done so anyway, and objects to such micromanagement by his uncle.

To his great credit, he doesn't dodge the uncomfortable question: is Toni's presence overbearing and suffocating? Nadal weighs "the fine balance" before concluding that his uncle, overall, has been a force for good - but it is not a judgement reached lightly.

There is, without doubt, more than a hint of the Tiger Mother phenomenon in this book. As Nadal reviews his childhood, the relentless discipline and practice, the unceasing pressure to endure and improve, he emerges as a living experiment in nurturing a champion. Some will argue that his success is proof that champions are made and not born. The truth is more ambiguous. His parents took an enormous risk with him. They judged that he had the talent to turn professional and the mental strength to endure an arduous regime of training and criticism. The evidence of his career suggests that their judgement was right. Yet what if they had been proved wrong?

There is a second, equally fascinating, theme to this book: vulnerability. Nadal reduced Federer to tears at the Australian Open final in 2009. In exposing Federer's vulnerable side, the Spaniard has made his rival all the more attractive - and yet Nadal exudes an even deeper vulnerability. What will happen if he one day questions why he is out there, scrambling and scrapping to the edge of sanity? Pain is bound up with his performance. You suspect that if he ever loses his fear of falling short, he might not be able to carry on at all.

Rafa: My Story is a terrific sporting memoir, full of memorable anecdotes and stamped with the authority of a ghostwriter who earned the complete trust of his subject. It is hard to imagine how Nadal could have done any more to get the best out of his own raw material. And it is to Carlin's enormous credit that the book is a true reflection of the man, in every sense.

Ed Smith is a writer for the Times (edsmith.org.uk)