Roger Federer, five times a US Open champion, let slip a golden chance to reach the final, eventually going down to an inspired Novak Djokovic 7-5 in the fifth set.
"Two years ago, Roger would have taken one of those match points," an American colleague said here on Saturday night, moments after the man who is considered by most to be the greatest ever to have played the game left the court a loser for only the second time in seven years.
It will be of absolutely no consolation to Federer that he was part of the best match of this year's US Open as Djokovic saved two match points at 5-4 in the final set and then broke the Swiss before holding his nerve under immense pressure to close out one of the biggest victories of his life. Federer's parting shot was to say that he would not watch last night's final between Djokovic and Rafael Nadal. Losing in the semi-final of a Grand Slam is marginally less painful than losing in the final, but only marginally. Federer is used to winning and this one will have hurt.
"It's a tough loss for me, but it's only going to fuel me with more motivation to practice hard and get back to Grand Slam finals, which I haven't been in for the last three slams," Federer said. "I feel like I'm playing well, and I would have deserved to be in the finals."
At the French Open, when he was outslugged by Robin Soderling of Sweden in the quarter-finals, the slow, wet conditions, Federer said, were against him. At Wimbledon, after he lost to Tomas Berdych of the Czech Republic at the same stage, he complained of back and leg injuries. This time, there were no excuses as he put himself in a winning position and failed to see it through.
An awful lot of credit has to go to Djokovic, who played brilliantly, throwing caution to the wind when he was down, as Federer has done so often in the past. But what will worry Federer most is that he was beaten on his own terms, beaten by the better player on the day and if it hadn't been for one or two pivotal moments in sets one and three, he could even have gone out in straight sets.
The temptation will be to suggest that Federer's time, if not quite gone, may be passing. Three times this year he has lost matches from match point up, in Indian Wells, Miami and now here. A fully fit Nadal, now 24, has taken his No 1 ranking and his French and Wimbledon crowns. At the age of 29, he is likely to suffer more and more niggling injuries, which take their toll at the highest level. And more worryingly, the fear factor he had when he was utterly dominant between 2004 and 2007 is slowly disappearing. Players used to think he was unbeatable; now they know he is not.
When great players fall from their peak, the decline can be steep and denial often comes into play. There was a hint of that from Federer on Saturday when he suggested luck played its part in his defeat. "When you lose a match point, they feel somewhat empty at the end because you have tried everything," he said. "Maybe it was luck. Maybe it was [because] he played well. Maybe you didn't pick the right shot; maybe he did."
Federer had beaten Djokovic in each of the past three years here, twice in the semi-finals and once in the final. The Swiss has always respected the Serbian but never feared him in the way he does Nadal. But for all Djokovic's courage on the match points and thereafter, it's hard not to think that the Federer of old would surely have finished him off.
"I wish I could say he hit only winners to get back and I played my very best tennis, but it wasn't the case," Federer admitted. "It was just a case of a tough situation to be in for both of us, and someone has to win. There are no draws in our sport. Obviously I like to see a match like this being two winners, but one guy had to win. It won't be written that way, unfortunately."
The world No 2 had not dropped a set on his way to the last four and had looked better than he had since he beat Andy Murray to win his 16th Grand Slam title at the Australian Open in January. With new coach Paul Annacone in his corner, he showed more eagerness to move forward and everything was working smoothly. Here, though, not only did his form waver, but his serve was below par. The Federer serve is arguably the most under-rated shot in tennis but when it doesn't click, he is vulnerable.
Federer will now take some time off to gather himself before the Masters 1000 events in Shanghai and Paris before the season-ending Masters Cup at London's O2, an event that he may now see as more important than ever, a chance to reassert his authority before the start of next season. It will be interesting to see if, under the guidance of Annacone, who coached Pete Sampras, he tries to come to the net more, shorten the points and not allow himself to get sucked into slugging matches from the baseline.
It still takes the world's best players to beat him, especially at the Grand Slams, so it is still too early to say that he will not win another Grand Slam title. But with a rejuvenated Djokovic, a rampant Nadal, a hungry Murray, last year's US Open champion Juan Martin Del Potro coming back from injury, and a host of other believers, it is surely only going to get more difficult. If he manages it, then he will be the greater for it.