Sportico is proud to partner with The Harvard Sports Analysis Collective, a student-run organization dedicated to the quantitative analysis of sports strategy and management, to bring our readers the excellent work coming from some of the brightest young minds in the country. This piece was written by David Arkow.
We are truly living in an unprecedented era of men’s tennis and of sport, where arguably the three greatest players of all time are playing at the same time: Roger Federer, Rafael Nadal and Novak Djokovic. Of the past 70 Grand Slams since Nadal won his first (at Roland Garros in 2005), only nine have been won by players other than the Big 3: Andy Murray (3), Stan Wawrinka (3), Juan Martin del Potro (1), Marin Cilic (1) and Dominic Thiem (1).
This near-monopoly is extremely impressive considering that the structure of tournaments means the Big 3 often have to face each other head-to-head in the draws. Their paths to Grand Slam victory are therefore much harder than that of dominant players from prior generations, because they frequently have to go through one (or both) of the other two all-time best players to achieve it. Just imagine if Nadal played in a different era and Federer and Djokovic never had to face him at the French Open—they would both likely have many more Slam titles to their names. In addition, as they age into their 30s these three have been able to hold off the up-and-coming competition, solidifying their reputation as the three greatest players of all time.
Still, sports fans are not satisfied with simply labelling each of the Big 3 as “one of the best.” But unlike other ongoing GOAT disputes (such as Michael Jordan versus LeBron James in basketball), the Big 3 are easier to compare with one another because they are contemporaries. While the debate is not yet settled and time will still tell, a current holistic analysis of the Big 3 reveals that Novak Djokovic is the greatest tennis player of all time.
Honorable Mentions: “Pistol” Pete Sampras, who won 14 Grand Slams, is without a doubt the greatest American tennis player of all time. He is considered the predecessor to Federer, since they had similar game styles: Both were grass court specialists, had big serves and had one-handed backhands. But Sampras retired at age 31, leaving room for speculation about whether he could have won more Slams. Retiring at an even younger age was Swedish “Ice Man” Bjorn Borg, who won 11 Slams before walking away from the sport at age 26. He won four consecutive French Opens and five straight Wimbledons. Then there’s the old-timers’ favorite, Australia’s “Rocket” Rod Laver, who won 11 Slams but wasn’t eligible to compete in any during the six pre-Open Era years (1963-1968) after he turned pro. Had Laver had been allowed to play in an extra 24 Slams, who knows how many more he would have won? Laver is also the only player to win the calendar Grand Slam (all four majors in one year) and he did so twice, in 1962 and 1969. But regardless of the circumstances, the Big 3 have combined for over 20 more Grand Slams than this other trio of greats, while facing tougher competition in the golden era of tennis.
When comparing the Big 3, most people often resort to the traditional criteria of Grand Slam titles. By that logic, Federer (20) and Nadal (20) would be tied ahead of Djokovic (17). However, this method is too simple, failing to take into account age, surfaces (hardcourt vs. clay vs. grass), head-to-head records and other tournaments. A more comprehensive analysis requires examination of a number of different metrics.
Grand Slam Titles
Roger Federer is about five years older than Nadal and Djokovic, so he would be expected to have more Grand Slam titles. To model their career trajectories, I graphed the number of Slams each player had won by age:
Djokovic, one year younger than Nadal, started out slowly and trailed his two rivals in the beginning of his career. But he picked up the pace in recent years and by age 32 had won 17 Slams—the same number Federer and Nadal had under their belts at that age. In contrast to Djokovic’s late bloom, Federer was stuck at 17 from age 30 to 34, which proves that he peaked the earliest and has been well into his decline. It does not seem likely that he will win another Slam (especially since he missed the second half of the 2020 season with his ongoing knee injury). If Djokovic is able to maintain his trajectory, then he looks likely to pass Federer in the next few years. Meanwhile, even though Djokovic and Nadal are on similar trends, the latter is extremely reliant on one surface—clay.
Djokovic also had the greatest peak Elo rating of the Big 3 (and by a decent margin) and currently has the highest Elo. His peak of age 29 was also the latest (likely because he was competing against a prime Federer and prime Nadal), whereas Nadal peaked at 27 and Federer at 25, which is a good sign that Djokovic, now 33, will continue to be a stronger contender at each Slam for many years to come. He’s spent 300 total weeks (and counting) at the No. 1 ranking, while Nadal lags behind at 209. Federer leads at 310 (and previously spent an impressive 237 consecutive weeks at No. 1) but is likely to be surpassed by Djokovic in 2021. Djokovic is known for his intense training regimen, strict nutrition plan and tenacity. The fifth set in tennis is a good measure of a player’s physical and mental endurance, and Djokovic has a greater all-time fifth-set winning percentage (76.2%) than Federer (57.4%) and Nadal (66.7%). Djokovic is also the most competitive on all three surfaces. These factors all make him likely to accumulate more Slams than Federer and Nadal, who are older, have more injury history and are less versatile.
The advantage of actual head-to-head data for the Big 3 is tempered somewhat by the fact that they are not all the same age and peaked at different times. Early in Nadal’s and Djokovic’s careers, Federer already had more experience, and he racked up wins against them. Now that he is older and they are in better physical condition, Federer has seen his head-to-head numbers decline.
Another caveat is that their individual playing styles make them better suited to defeat certain opponents over others. Consider a baseball example: Two-time Silver Slugger winner Anthony Rendon (a right-handed hitter) has a .171 career batting average against Jacob deGrom (right-handed pitcher) while Justin Bour (left-handed hitter) has a .364 career batting average against deGrom. This would suggest that Bour—who now plays in Japan—is a much better hitter than Rendon, but we know this is not true; deGrom is simply a better matchup for a lefty hitter. Similarly, Federer’s playing style does not match up well with Nadal’s because Nadal’s high lefty spin kicks up into his one-handed backhand, which is hard to handle—but he beats up on the rest of the ATP competition more than Nadal does.
When broken down into the one-on-one pairings, Djokovic proves his dominance over both Nadal and Federer. While Djokovic has only a slight advantage on this metric, a further breakdown of their record by surface reveals more to the story.
The majority of matches are played on hardcourt, followed by clay, then grass. This suggests that hardcourt excellence could be more valuable than playing well on other surfaces in determining the GOAT. In Big 3 matchups, Djokovic has the highest winning percentage on both hard (62%) and grass (63%) while, as expected, Nadal leads on clay (78%). Interestingly, Nadal is well behind both Djokovic and Federer on hard (34%) and grass (38%).
Completely discounting Nadal’s dominance on clay would be unfair, but recognizing his overwhelming reliance on that surface is important. Especially when determining the greatest men’s tennis player of all time, versatility across all surfaces should matter. Thirteen of Nadal’s 20 Grand Slam titles have come on clay (he has only lost twice in his career at the French Open), and as he has aged, that partiality has become even more lopsided. If most tournaments were played on clay, that would definitely change the GOAT discussion, but that is not the case. As a result, Nadal’s Slam count might be a little inflated by his racking up titles at the French Open.
There is no doubt Nadal has earned the title of King (and GOAT) of Clay, but Djokovic looks to be the overall GOAT based on his all-around excellence and potential for even further growth. Clay is the most demanding surface (because match times are longer due to longer rallies), and it has taken a toll on Nadal’s body as his injury-riddled career can attest. Meanwhile, Djokovic is still in his prime physical shape, and he looks to still be near his peak.
Predicting Djokovic’s Future Slams
In order to predict the number of Slams that Djokovic is expected to win over the remainder of his career and see if he can eventually surpass Federer’s and Nadal’s marks, I graphed the distribution of Slams won by age for all players who have at least five Slam titles in the Open Era (this sets a baseline for being a very good player among good competition). From that graph, I found the “average peak age” of when the most Slams were won (24) as well as the median age for when these players won their last Slam (31.5). From this I graphed a best-fit line for the decline of these players, seeing what percentage of Slams they lost per year as they aged.
Using ESPN simulated probabilities for Djokovic winning each Slam in the 2021 season and the top Open Era players’ aging curve, I could find how much his odds of winning each Slam would decline per year, projecting six years into the future. Given his late peak, surface versatility, fitness and lack of injuries, Djokovic can be expected to compete until he is 39 (Federer’s current age). I then added up the overall probabilities to see how many more Slams Djokovic is expected to win: 4.4, which would give him a career total of 21.4.
Even still, this method may underestimate Djokovic’s odds. Calculating an expected probability for winning each tournament is very difficult as it depends on the 128-player draw, who advances in the draw and more. It’s hard to predict the future competition, especially with emerging players like Dominic Thiem, who might pose more (or less) of a threat than people expect. Furthermore, if Nadal retires early, Djokovic will have an easier path to titles (especially in the French Open). Finally, this method uses data from past players to predict how Djokovic will decline. But modern players (especially Djokovic) have access to improved training regimens and injury-prevention technology, so they are likely to stay competitive longer than their predecessors. Also, we’ve already seen that Djokovic’s peak age (29) is much later than the average of the other Grand Slam greats (24), so perhaps his career could have an even longer tail if he maintains his physical shape. As a result, Djokovic may have even higher odds than these projections would suggest.
On the other hand, unforeseen injuries could sideline Djokovic and accelerate his decline. Predicting the future is difficult, but even using this conservative estimate, Djokovic still is likely to pass Federer in Grand Slam titles—and possibly Nadal as well.
Novak Djokovic has a winning record against both Roger Federer and Rafael Nadal, sustained the longest peak, possesses the most surface versatility and is on trend to pass the other two in the Grand Slam title race. These are all factors which sports fans consider the most important when crowning GOATs: head-to-head records or individual statistics, longevity, peak performance, versatility and championships. Djokovic leads in almost all of these metrics. He might not have the grace of Fed or the flare of Rafa, but Djoker will ultimately be the GOAT.
David Arkow (’24) is an economics major and a member of the Harvard men’s varsity tennis team.