David Leggat: Roger's dilemma - should he stay or should he go?

So here's the question: is the greatest of modern players, perhaps of them all, finished as a Grand Slam champion?

To absolutely no surprise, Roger Federer says of course not.

"I wouldn't be here if that wasn't the case," he said after losing his five-set quarter-final to the explosive Frenchman Jo-Wilfried Tsonga.

Tsonga danced a jig on centre court after coming from two sets behind to beat the legend. Fair enough too. He'd earned that particular right.

The Swiss genius is 29. If he's to win a seventh Wimbledon crown he will have to do so after entering his fourth decade.

The last man to manage that was Arthur Ashe, the highly esteemed American who triumphed over brash Jimmy Connors at 32 in 1975. So, not impossible, but far from easy.

Now consider a couple of other factors. Between 2003-07, Federer won 12 out of 18 grand slam titles, starting with toppling Mark Philippoussis on south-west London's grass.

Since clouting Andy Murray in three sets at the Australian Open last year, Federer has failed to win any of the last six grand slams.

Look at the Tsonga match. In 178 previous grand slam matches, Federer had never lost from two sets to love up. Never.

You might argue that it had to happen at some point, and indeed a case can be made that much of this evidence, taken on its own, should not count unduly against Federer.

But there's an accumulation aspect to this; just a feeling that the bell is about to toll on Federer's reign.

The way he whizzed through the first set against Tsonga suggested all was well in Fed-land. It would be wrong to leave Tsonga's contribution out. He was magnificent, full of spirit and Federer was right to argue that it wasn't as if Tsonga had been lucky or that Federer had played poorly.

A case, maybe, of "these things can happen". But here's the point: for so long they didn't when Federer was at his office. Now they are.

Throw in Novak Djokovic's unseating of Federer from the Big Two, certainly on the ranking list, and in actual performance this year.

Should Federer quietly walk away? Not unless he really wants to, but here you come to the dilemma of all great champions, knowing when to hold and when to fold.

He remains an adornment of the game, one of the few in a sport dominated by physicality and power possessing the great artist's touch.

So here's an idea: Federer climbs the mountain once more, wins the US Open in New York in September, and packs up his bag for the last time.

Great champions should go out that way. You wonder how fiercely the desire burns, deep inside.

Does he still possess the same degree of cold-eyed ruthlessness, or is his articulating on the subject more lip service these days? Only Federer knows, and he might surprise us all by winning another grand slam or two. But younger gunslingers are on his trail, and that's not even considering world No 1, the 25-year-old Spanish machine Rafael Nadal, who has won 17 of their 25 clashes.

Of late, there's been talk of the big four of men's tennis: Nadal, Federer, Djokovic and Murray. You wonder how much longer that quartet will remain intact in those terms.

It's not as if Federer is reaching for the armchair and he'll still whip most of those on the other side of the net. But for someone who scaled the loftiest heights, is that sufficient?