At the time, Rafael Nadal stood at six Slams while Novak Djokovic had a solitary AO title which he had bagged in 2008.
Fast forward 10 years, and the scenario is staggering to say the least. While Federer is still leading the charts with 20 Slams, Nadal and Djokovic are staring down his throat with 19 and 17 titles respectively.
No one would have imagined a life-cycle of just a decade for the Swiss' hegemony. With an aging Federer, the 2020s decade starts with the all-important question as to who among Nadal and Djokovic will dethrone him from the top spot.
While Nadal has been consistent enough to maintain his claycourt dominance, Djokovic has been ruthless in his intent of crushing opponents on every surface. To give a bit of perspective, out of the 40 Slams in the last decade, these two won 26 titles (65%), while Federer won just five (8%).
To the people playing Federer's age card, Nadal and Djokovic won five and nine Slams respectively aged 28-33, while Federer won just two during these five years of his career.
Going forward, the biggest advantage these two possess is age. Federer, still performing well at 38, has set a precedent for others that with proper fitness management, tennis can be played at the highest level even into your late 30s. Djokovic (32) and Nadal (33) have at least 3-4 years of professional tennis left. Assuming that they both play 15 Slams more, it's hard to imagine them not winning at least 3-4 titles each.
Another aspect that makes these two different from the rest is their ability to bounce back from impossible situations. The image of a forlorn Nadal exiting the US Open in 2015 is still fresh in everyone's mind. With moist eyes staring up the skies, he looked gutted.
Many had predicted then that it was the end of the road for the Spaniard. But he came back and won the French Open in 2017, ending his three-year Major drought and followed it up with four more titles in the next two years.
Djokovic had looked clueless in his 2016 Wimbledon loss to Sam Querry before crashing out of the Rio Olympics (2016) in the first round. Seeing a sobbing Djokovic was a rare sight. It was evident then that something was not going right for the 12-time champion.
He struggled through physical and personal turmoil for two years before eventually bouncing back at Wimbledon 2018, and hasn't looked back since.
The players that can stop Djokovic and Nadal, are the Next-Gen - Dominic Thiem, Daniil Medvedev, Stefanos Tsitsipas and Alexander Zverev. This group is touted as the next Big 4 in tennis.
However, only two of them have come close to winning a Slam so far - Medvedev at US Open 2019 and Thiem at Australian Open 2020. They were eventually beaten in the finals by Nadal and Djokovic respectively.
The relevant question is: who among these players can break the Big 3 dominance in Grand Slams? Such dominance has not been witnessed in tennis or any other sport. In the 17 years since Federer won his first Slam in 2003, he, Djokovic and Nadal have won a staggering 55 out of the 68 (~80%) Majors played.
For fans to continue seeing Federer on top of the Slam pile, the younger group would have to engineer a dramatic turnaround in 2020.
While the Next-Gen has shown the ability to beat the Big 3 in ATP events, inconsistency in Grand Slams has hurt them badly. Defeating these legends in a best-of-five sets final is a different beast altogether.
Tsitsipas and Zverev have reached the semi-final of a Grand Slam just once in the 13 and 21 Majors they have played. While Medvedev looked supreme the whole of last year, he is struggling to find the same touch since his four season-ending losses in 2019.
Thiem looks the most potent, having reached the final at Roland Garros 2019 and Australian Open 2020. He has also overtaken Federer as World No. 3 with his performance at the Rio Open.
With the clay season around the corner, Thiem is the best bet apart from the Big 3 to win a Grand Slam title.
In no way is Federer less competent at winning Slams, but seeing him win seven matches on the trot seems a distant dream given his recent injury woes. It was heartbreaking for his fans to see him squander two championship points on serve at Wimbledon 2019, a day that will likely haunt him for years to come.
That was probably the closest he'll ever get to winning a Slam again with Djokovic and Nadal in such good form.
It would be great to see the Swiss win a couple more titles and retain a chance of maintaining his supremacy. Looking at his current form though, the only shot he seems to have is at Wimbledon, with grass suiting his style of play.
If he fails to come good on the lawns of SW19, it would be just a matter of time before Nadal and Djokovic equal or surpass his tally - assuming the Next-Gen doesn't rise to the occasion.
Though Nadal is just a Slam away, Djokovic is in top form and has a versatile game, making him the front-runner to end with the highest titles. Nevertheless, Roland Garros is the next Major, with Nadal having the first shot at equaling Federer's tally - something that could be the last nail in the coffin for fans who are hoping for a miracle from Federer.
Whosoever ends up with the highest Slams, the coming couple of years will certainly go down as the most pivotal times in tennis history - with viewers getting to watch three legends battle it out for the tag of the 'GOAT'.