The years may finally be catching up with Roger Federer but the US Open’s conditions were brutal

Federer is normally the coolest of customers but was clearly in trouble and admitted afterwards that in some respects he was just happy for the match to end

We have been here before. Roger Federer’s shocking defeat to John Millman in the fourth round of the US Open here in the small hours of Tuesday morning has inevitably provoked debate about the world No 2’s future, but anyone who is thinking of consigning him to history might be advised to think again.

For years there has been speculation as to how much longer Federer can continue at the top. The doubting voices grew in number when he lost to Sergiy Stakhovsky, the world No 116, in the second round at Wimbledon in 2013 and rose significantly when he announced in the summer of 2016 that he was taking off the rest of the year because of a knee problem.

By the time Federer returned to competition at the start of 2017, he had won only one Grand Slam title in the previous seven years. In the seven years before that, between Wimbledon in 2003 and the Australian Open in 2010, he had won 16.

Some might have expected Federer’s return in 2017 to amount to little more than a farewell tour, but against all expectations he won three of the next five Grand Slam tournaments and even recaptured the world No 1 ranking. At times his tennis in the last 20 months has been better than ever.

However, the world No 2’s level has dipped this summer. Federer was worn down by Kevin Anderson in the quarter-finals at Wimbledon, outplayed by Novak Djokovic in the final at Cincinnati and outlasted by Millman here.

At 37, might the years be catching up with him at last? Maybe, but in assessing his latest setback it would be wrong to downplay the significance of the brutal conditions that have prevailed here at Flushing Meadows. Federer said after his defeat to Millman that he had struggled in the heat and humidity, which has sapped the energy of many of the world’s best players over the last fortnight.

It has been hot, with temperatures up into the mid-30s, but it is the humidity that has been the major factor. Numerous players have called for the doctor in matches. Novak Djokovic has twice looked on the brink of exhaustion, Lesia Tsurenko said on Monday that she had never felt worse on a tennis court and there have been many retirements. The conditions became so stifling that all junior matches were halted at lunchtime on Tuesday.

Roger Federer suffered a surprise defeat at the US Open (AFP/Getty Images)

Playing at night, as Federer did, can help, but it was hard to remember seeing sweat pour off the Swiss as it did on Monday evening. He is normally the coolest of customers but was clearly in trouble and admitted afterwards that in some respects he was just happy for the match to end.

Of course there will come a time – and it is likely to come sooner rather than later if it has not arrived already – when Federer’s decline will be clear. He might then be tempted to put away his rackets for good, but he still loves his lifestyle, particularly when he is able to travel the world with his family, and loves playing tennis.

Although it would be hard to imagine him continuing to compete if he were to drop out of, say, the world’s top 30, until that happens we can expect him to carry on playing.

Federer always plans his schedule at least a year in advance and has already made commitments for 2019, such as planning to start his season at the Hopman Cup in Perth. You could imagine that he would also like one last crack at an Olympic gold medal in singles in Tokyo in 2020.

For the moment his next focus will be the Laver Cup – the team event which is run by his own management company – in Chicago later this month. Thereafter he is expected to play in next month’s Shanghai Masters, his hometown tournament in Basle, the Paris Masters and the year-ending Nitto ATP Finals in London.

The end will come eventually but just about everyone in tennis – from the fans to the tournament box offices and from administrators to TV schedulers and journalists – will be hoping that the greatest player in history hangs around for a good while yet.