What a pity that David Foster Wallace is not alive today. The American novelist, formerly a junior tennis prodigy in Illinois, was once the leading chronicler of Roger Federer’s greatness.

It was Foster Wallace who described Federer’s forehand as “a great liquid whip” and the man himself as “a creature whose body is both flesh and, somehow, light”. He rolled up a salvo of epigrams into a classic New York Times essay: “Roger Federer as Religious Experience.”

Had he lived, Foster Wallace might have reached an even higher plane of ecstasy today. At the age of 35 years and 11 months, Federer is about to play his 11th Wimbledon final. And over the first two-thirds of the 2017 tennis season, he has delivered the greatest tennis of his career.

If you don’t believe me, just ask Magnus Norman, the man widely seen as the world’s leading coach. At Queen’s last month, Norman told Telegraph Sport “For sure, Roger and Rafa [Nadal] are playing better now than they were ten years ago. They play closer to the baseline and they move much better, much faster. That’s the evolution of the game.”

Few Wimbledon finals have been as imbalanced as this one in terms of popular interest and support. Marin Cilic is perhaps less of an underdog than Cedric Pioline, the little-known Frenchman who mounted a doomed attempt to overcome Pete Sampras in 1997. But only just.

Pete Sampras after defeating France's Cedric Pioline in 1997 credit: AP

With respect to Cilic – who is both a fine player and a charming man – he is still only Croatia’s second-most-famous tennis player after his own former coach, Goran Ivanisevic.

Yes, he might have gone on David Letterman’s show after lifting the US Open title in 2014 – a victory that Ivanisevic described as “fresh blood, fresh air for tennis”. But he has not inspired the Nobel Prize-winning author, J M Coetzee, to write to his fellow novelist Paul Auster, saying, “I have just seen something like the human ideal made visible.”

Men of letters usually consider sport to be beneath their notice. Yet Federer’s artistry takes him into a different sphere, where he is as likely to be compared to Mikhail Baryshnikov as to Rod Laver. The same artistic flair also makes him overwhelmingly popular with the everyday tennis fan.

To quote Ivanisevic again, when you play against Federer, “you are also playing 20,000 people”.

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However Sunday’s match progresses, one suspects that Wimbledon 2017 will be remembered not for dodgy grass, nor for rows over sexist scheduling, but for what happens to Federer. Either he becomes the first man to win an eighth Wimbledon title, overcoming the record he now shares with Sampras and the 19th century gentleman amateur William Renshaw. Or he falls at the last, showing an unexpected hint of mortality on the same Centre Court that turned him into a sporting deity in the first place.

For today’s ticket-holders, it is a win-win situation. If Federer wins, there will be a party in SW19, no matter how easily the job is done. If he is to be beaten, then Cilic will have to produce one of those note-perfect attacking performances – think not only of his own dash to the title in New York three years ago, but also of Stan Wawrinka’s win over Novak Djokovic in the 2015 French Open final – that leave scorch-marks on the court.

Roger Federer celebrates after winning against Czech Republic's Tomas Berdych credit: GETTY IMAGES

The one thing we can discount is any sort of Federer freeze. Retired tennis champions say that big points become harder to play as you get older. No matter how hard you try to block it out, you know in the back of your mind that you might never get another chance. You grip the racket handle as if it were a lifebuoy when you should be cradling it like a baby.

Yet Federer, made of different stuff in so many ways, seems immune to such flickers of self-consciousness. Is he too focused on creating art? Or just constitutionally immune to self-doubt? Either way, he has played his whole career with the cavalier instincts of Marshal Foch, the French general whose response to a setback was to roar, “Situation excellent. I will attack.”

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Rather like Nadal’s frictionless progress through last month’s French Open, Federer has yet to drop a set. On Friday, when faced with the thunderous strokeplay of the heavy-thewed Tomas Berdych, he looked disappointed even to commit the occasional error, throwing a mini-tantrum when one of his backhand slices caromed off the frame.

The only time he has played with nerves all fortnight was during his second-round match against Dusan Lajovic – because “I didn’t know my opponent very well”. Otherwise, he has been building with each round towards some as-yet unguessed peak. Should it arrive today, then Cilic – like Berdych in the previous round – could be reduced to the status of an accomplice or sidekick, providing the set-ups for Federer’s punchlines.

It is to Cilic’s advantage that he has beaten Federer before at a grand slam, in the 2014 US Open semi-final. Yet there might also be scarring from last year’s quarter-final here, where he held three match points for a four-set win.

“Marin lost that game, rather than Roger winning it,” said Ivanisevic earlier this week, “because he did not get one return in on the match points. Roger is like someone from a film. You have to kill him about 77 times to win.”

The thought might not be as elegantly expressed as a Foster Wallace essay. But it captures the magnitude of Cilic’s task today.