How rash we were to doubt him. When Rafael Nadal headed to Monte Carlo for the start of the European outdoor season in April, the biggest question was whether the Spaniard would ever rescale the heights. Having struggled to recover from his knee problems of the previous year, he had gone 11 months without winning a tournament and lost 12 of his previous 14 matches against top 10 opponents.
Five months later the question on everyone's lips is a very different one. Is the 24-year-old Spaniard on course to become the greatest player of all time?
It was little more than 12 months ago that the sport was acclaiming Roger Federer as the best in history after he became only the sixth man to win all four Grand Slam titles and overtook Pete Sampras' record haul of 14 major crowns. Nadal, however, not only expanded that elite group of men to seven with his memorable 6-4, 5-7, 6-4, 6-2 victory over Novak Djokovic in the final of the US Open in New York on Monday night, but continued to outstrip his great rival in terms of the age at which he has reached his milestones.
At 24 years and three months (Nadal's current age), Federer had won six Grand Slam titles. Nadal has already claimed nine and has won the "career Grand Slam" three and a half years earlier than Federer did. He has also done it at a time when the Swiss has been at his peak.
"He has the capabilities already to become the best player ever," Djokovic said in the wake of Monday's final. "He's playing the best tennis that I've ever seen him play on hard courts. He's improved his serve drastically. There's his speed, his accuracy, and of course his baseline game is as good as ever.
"He's getting better each time you play him. He's so strong mentally and dedicated to this sport. He has lots of time if he holds on physically for the next five, six or seven years. He has the game now for every surface and he's won every major. He's proved to the world that he's the best at this moment. There's no question about it."
When Nadal won his fourth Grand Slam title – all of them at the French Open – two summers ago he was still regarded by some as a clay-court specialist. Winning on grass at Wimbledon a month later changed all that and when he added the Australian Open on a hard court in 2009 he completed the set of Grand Slam titles on different surfaces.
However, Nadal had never gone beyond the semi-finals of the US Open, where the conditions and the time of year – after a summer in which he had always given everything in the clay and grass-court seasons – always counted against him. Playing on hard courts also puts enormous stress on Nadal's suspect knees. This year careful management of the problem and a lighter playing schedule have brought him through the summer unscathed.
Nevertheless, it would be wrong to assume that he will overtake Federer just because he has achieved more at an earlier age. Nadal's all-action style of play puts much greater demands on the body – Federer is lighter on his feet and wins points more quickly through his more aggressive game – and it remains to be seen whether the Spaniard's knees will continue to hold up.
If adapting his game to win at Wimbledon was regarded as Nadal's greatest single achievement, the manner of his victory in New York represents an arguably finer triumph. The combination of a fast surface, intense heat and zippy Wilson balls make the conditions at the US Open arguably quicker even than at Wimbledon – and certainly not ideal for the big swing Nadal uses on his heavily top-spun forehands.
His serve, which had been a comparative weakness in the past, was also seen as a problem, but, remarkably, no US Open champion has been broken on fewer occasions since such statistics were first recorded 19 years ago. Having changed his grip just days before the start of the tournament, Nadal served with significantly more power and variety.
He equalled the record of Andy Roddick, who dropped his serve only five times in 2003, and would have beaten it had Djokovic not broken him three times. The Serb also stopped the Spaniard becoming the first player in the Open era to win in New York without dropping a set.
Nadal always believed that playing on grass actually helped to compensate him for his serve. "Even with not such a good serve it was just as effective at Wimbledon as my current serve has been here," he said. "I think hard courts were always the most difficult surface for me, especially on serve because I had to play hard to win every point. The serve probably made the big difference in this tournament."
He added: "If I can keep serving like this and have the 'free' points on my serve that I had during all this tournament it should be a big change for me. I can also play more aggressively and with more calm when I am returning. I can change a lot. I can improve everything: volleys, my position on court, being more inside the court. I've improved a lot since last year, but it's never enough."
Nadal said the Barclays ATP World Tour Finals in London in November was his big target for the rest of this year. "That's probably the last big tournament that I haven't won," he said.
The ever-modest Spaniard, who thought that winning the US Open was an even greater dream than winning all four Grand Slam titles, dismissed talk about being the greatest. "The number of titles Roger has won says he's much better than me and I think that will be true all my life," he said. "Roger has always been an example to me, especially because of the way he has improved his tennis throughout his career."
Nadal said that the second half of last year, when he had to cope with the break up of his parents' marriage and his injury problems, had been hard. "It wasn't an easy year, but at the same time when you come back after you've been through times like this you appreciate how difficult it can be to win titles," he said.
The world No 1 said that Djokovic's excellence had forced him to play his best match ever in New York. Djokovic's career seemed to have reached a plateau following his Australian Open triumph in 2008, but his rediscovered aggression, coolness under pressure (he saved 20 out of 26 break points against Nadal) and resilience have entrenched him firmly in the group of contenders for major honours. The 23-year-old Serb has reclaimed the No 2 spot in the world rankings from Federer, whom he beat in the semi-finals in the outstanding match of the tournament.
The sportsmanship Djokovic showed at the end, giving Nadal the warmest of embraces and hailing his greatness, underlined what a golden age this has become for tennis, both in terms of the ability and the grace of its leading men. For a British audience, the big hope is that Andy Murray can remain a part of that elite group. He is, after all, the only man to have beaten Nadal in a Grand Slam tournament this year.
How Nadal won his career Grand Slam
13 Sept 2010 (Age: 24): Defeats Serbia's Novak Djokovic 6-4, 5-7, 6-4, 6-2 to complete the career Grand Slam in New York
5 June 2005 (Age: 19): Won as fourth seed for first of five titles at Roland Garros (also won in 2006, 2007, 2008 and 2010)
6 July 2008 (Age: 22): Overcame Federer in a five-hour epic seen as one of the best-ever finals. Also won at SW19 this year
1 Feb 2009 (Age: 22): Left Federer in tears after another five-set marathon, winning in Melbourne at the fifth attempt
Seven wonders of world tennis: Career Grand Slams
Fred Perry (Eng)
Aus: 1934; French: 1935; Wimbledon: 1934, 1935, 1936; US: 1933, 1934, 1936
Don Budge (US)
Aus: 1938; French: 1938; Wimbledon: 1937, 1938; US: 1937, 1938
Rod Laver (Aus)
Aus: 1960, 1962, 1969; French: 1962, 1969; Wimbledon: 1961, 1962, 1968, 1969; US: 1962, 1969
Roy Emerson (Aus)
Aus: 1961, 1963, 1964, 1965, 1966, 1967; French: 1963, 1967; Wimbledon: 1964, 1965; US: 1961, 1964
Andre Agassi (US)
Aus: 1995, 2000, 2001, 2003; French: 1999; Wimbledon: 1992; US: 1994, 1999
Roger Federer (Swit)
Aus: 2004, 2006, 2007, 2010; French: 2009; Wimbledon: 2003, 2004, 2005, 2006, 2007, 2009; US: 2004, 2005, 2006, 2007, 2008
Rafael Nadal (Sp)
Aus: 2009; French: 2005, 2006, 2007, 2008, 2010; Wim: 2008, 2010; US: 2010