In a post-match conference at the US Open tennis tournament after he beat Paul-Henri Mathieu in the third round, Roger Federer said Rafael Nadal “needs to win the US Open" to stake his claim to be the Greatest of All Time (GOAT), but added that he was confident Nadal would accomplish this. The Spaniard did not win any title this US hard-court season, but nine days after Federer’s statement, became the seventh man to win the career Grand Slam (all four Grand Slam titles—Australian, French, Wimbledon and the US, but not all in the same year) and at 24, the youngest player to do so.

Nadal had staked his claim to being the GOAT; the debate just got interesting.

It is ironical that Nadal should be spoken of in the same breath as Federer, when just a few years ago the latter, now the world’s No. 3 ranked player, used to clinically destroy opponents. In 2004 and 2005, Federer won 11 titles each; the highest ever in a single year. He won 81 of the 85 matches he played in 2005 (a win-loss percentage of 95.3%). In 2006, he broke that record by winning 12 titles, including three Grand Slams, becoming the first player in the open era (since 1968) to win at least 10 titles for three straight years.

Between 2004 and 2006, he won 247 matches and lost just 15 (94.3% wins), with Nadal being the only player to beat him more than once during that stretch. In the race to the top, Federer destroyed practically everyone, except Nadal. A little flaw in Federer’s otherwise picture-perfect career, Nadal would prove to be Federer’s biggest nemesis and now even threatens to upstage him in the GOAT race.

Owning Federer

But is one chink in the armour reason to worry? Tennis experts believe it’s important to score over your closest rivals if you want to stake a claim to the GOAT trophy. Of the 21 times they’ve played each other, Nadal has won 14,

including their first encounter in the third round of the ATP Master Series at Florida in 2004, which he won 6-3, 6-3.

“It is a significant statistic, even more so because Nadal has won three different Slam finals against Federer, compared to one for Federer. Nadal has been relentless," says David Law, BBC Radio commentator and communications director of the ATP Champions Tour—a tennis circuit for former World No. 1s, Grand Slam singles finalists and Davis Cup winners.

The contenders: Age is in Nadal’s favour (Reuters), while Federer (right) has had a relatively injury-free career so far. (AP)

“Federer owned everyone in his career, except Nadal. Nobody has owned Nadal in his career, not anyone," says Brad Gilbert, a former tennis professional who has coached Andre Agassi and Andy Murray.

Surface doesn’t matter

Winning Grand Slams separates the men from the boys. But that is not enough, experts say, to be counted among the best. “Being able to win on all surfaces is important," says Gilbert over the phone from the US. He adds that former No. 1 Pete Sampras’ statistics “would have been up there" had he won the French Open; the one Grand Slam he missed in an otherwise memorable career. Sampras also finished the year-end as the No. 1 player six straight times in his career and is second on the all-time Grand Slam list with 14 titles. Rod Laver—who many consider the GOAT—may have won all four Grand Slam titles in the same year, twice in his career, but in his time three of the four (Australian, Wimbledon and the US) were played on grass. Bjorn Borg, who has 11 Grand Slam titles, avoided the Australian Open for the greater part of his career (he only played there twice). As Law puts it: “Only those who have won all four can be considered. Sampras and Borg are truly great, but they will always have that one (question) mark against them."

Holding on to the legacy

With 16 Grand Slam titles, Federer is armed with a new coach and a brand new attitude—he wants to take this tally to 20. That Federer is “not yet finished" is something Cliff Drysdale, ESPN announcer and former ATP professional, is quick to point out. “I feel he has another three Grand Slam titles in him. That way, Nadal is not shooting for 16 (Federer’s current tally), he’s going to shoot for 19," he predicts.

Federer, like Nadal, wrapped up his career Slam by winning his first French Open in 2009. He has finished as the year-end No. 1 five times. Part of Federer’s legacy is his seemingly superior genetics—his injury quotient is much lower than others on the ATP Tour. For instance, Federer has not skipped a single Grand Slam since 2000.

But age seems to be in Nadal’s favour. He got his career Slam at 24 and has nine in total. Federer is 29 and has 16 Grand Slam titles in his kitty. Federer has won 16 of the 45 Majors he’s played so far. Nadal’s nine come from playing in just 22 Majors.

Gilbert says we went from “Federer to Nadal as quickly as we moved from Sampras to Federer. Sometimes, we have to wait for 20 to 30 years between two great players; Federer and Nadal are two of the greatest players of all time," he adds.

That’s not to say that Federer is done. Law says, “Nadal has to win another five or so (Grand Slam titles) to be considered better than Federer. We have to wait another four years to get a more definitive answer. But it is fun to compare the two."

Nadal’s coach (and uncle) Toni Nadal agrees. Asked if Nadal can be considered among the best of all time, he was quoted in news agencies as saying: “I don’t know if he’s part of that group. Ask me in five or six years, and maybe I can say."