If tennis players had transfer fees, what would Roger Federer have been worth at his best? Let’s put it this way — a lot more than Gareth Bale.

Federer at his peak was not merely the greatest tennis player of his age. (Although he was certainly this.) He was not even simply the greatest tennis player of any age. (Although he was probably this, too.)

Federer was better than that. History ought to place him among the best of the best — a legend who transcended his sport, as did Pele and Michael Jordan, Don Bradman and Tiger Woods. It is hideous to watch him wane.

At the beginning of this summer, Federer was dumped out of Wimbledon 6-7, 7-6, 7-5, 7-6 by the then world No116 Sergiy Stakhovsky, a man who comparatively, and without meaning to do him down, was a nobody.

This week, at Flushing Meadows, it got worse. Tommy Robredo is ranked 22nd in the world and was seeded 19th in the US Open. But he swatted Federer like a bluebottle on Tuesday, winning in straight sets, 7-6, 6-3, 6-4. Federer’s fall to Robredo was even more distressing than the serve-volley mugging Stakhovsky inflicted at the All England Club.

Against a good player, Federer just looked…ordinary. He is dropping through the rankings and the world of tennis like a plumb-weight through a murky fishpond. It is more than possible that he will now miss the ATP end-of-term finals at The O2. After his defeat, he said he was “pretty shell-shocked”. Spare a thought, Roger, for the rest of us.

The fact that a champion’s decline is inevitable does not make it any less unbelievable when it comes. Very few sporting kings have either the freedom to choose or the ability to recognise their reign is over; to abdicate before they are deposed.

Sir Alex Ferguson bowed out of football with a Premier League victory last season, Frankel went out to stud with a record of 14 victories from 14 races, Floyd Mayweather is working through his boxing endgame, angling to retire with a perfect record and a perfect bank balance: these are the closest things that recent sport has seen to a great man (or, in Frankel’s case, a great hoss) leaving while he is still unarguably the boss.

Federer, however, is already taking the ghastly first steps along a path trodden by greats such as Muhammad Ali, Michael Schumacher and — dare we add — Brian O’Driscoll?

The reactions are slipping, the limbs are stiffening, the mind is tiring. Unworthy opponents are already earning their pensions in after-dinner engagements to talk about the day they scalped a great. But the great goes fighting on because fighting is all he has ever known. “I want to play better. I know I can,” said Federer this week.

We don’t doubt the first point.

But let’s be blunt. Federer is 32, he is done for, he should retire. The losses won’t erase any of the honours on his magnificent record of 17 Grand Slam singles titles. Like David Beckham, Federer will keep his lucrative sponsorships and his global fans once he retires.

But this succession of late-period defeats will soon start to corrode his legend. One last, great day may lie ahead. But even if it does, it will be surrounded by far too many ignominious ‘Robredo days’ to make the prize worth the pain of the chase.

Watching Federer in his prime was never an experience of emotional abandonment in the way that watching, say, Rafael Nadal, can be.

But the Swiss was always a beautiful, unruffled, technical and graceful player — as correct as clockwork and for a time virtually impervious. He combined balletic poise with pitiless aggression. He was the complete player.

Even after 2008, when a younger generation, led by Nadal, found ways to beat Federer, it felt not so much as though he was in decline; more that Nadal, Novak Djokovic and, more recently, Andy Murray had met the challenge of reaching the Federer standard.

Now Djokovic and Murray are at their peaks and Nadal is simmering, his career somewhere around the point that Federer’s was at three years ago. As they blaze on, Federer’s candle is guttering.

There is no nice way to say this — it is time the greatest tennis player in history hung up his sweatbands. He will be feted all the way into retirement. But there is no point delaying any longer.

This D-Day is about inbreds and kids

The stars — well, ish — of transfer deadline day were the fans who turned up to yahoo behind Sky Sports reporters at grounds all over England. They varied, club to club. Arsenal: 15-year olds with smartphones, trying to be moody and funny at the same time. Manchester United: many inbreds, some toothless. Tottenham: actual children, many of whom should have been in bed. QPR: literally just four bored blokes in polo shirts, one with a JD Sports bag. It was a good exercise in social profiling.

Football economy is hardly economical

Is Gareth Bale ‘worth’ £86m and £300k — or whatever — a week? Sepp Blatter was one of several old men this week shaking their heads at football's riches. But of course, Bale is ‘worth’ whatever Real Madrid care to pay. Is Justin Bieber ‘worth’ the $130m or thereabouts he has in the bank? Most right-thinking people with ears would say no; legions of Beliebers would say yes. So he is. And thus, Bale. It’s the economy of entertainment, stupid.

Even failure won’t shock us to action

Greg Dyke’s ‘State of The FA’ speech over lunch yesterday identified plenty of the obvious problems with the England football team, including most obviously a declining pool of senior players and a general subordination of national interests to the Premier League’s. But what is the incentive for change? English club football is a booming international business which can hardly be shackled or shepherded by the toothless FA. Change will take an apocalyptic shock — perhaps even greater than failure to qualify for Brazil 2014.

Irish can’t always let us hit them for six

Sure, there was mischief in an England cricket side captained by Eoin Morgan thrashing Ireland in this week’s ODI. But the most interesting moment was Irish captain Will Porterfield reaching his century by thrashing Boyd Rankin over the leg-side boundary for six. Ireland have some very talented players: how much longer will they allow them to cross St George’s Channel for international careers? The Irish want to be a Test nation by 2020. To get there, they need to keep men like Porterfield.