Jun 5, 2020
Jun 5, 2020

Who is the tennis GOAT? A view from the betting markets

Using Grand Slams to assess performance

Analysing performance against expectation?

Who comes out on top in head-to-heads?

Who is the tennis GOAT? A view from the betting markets

This generation of tennis fans have been blessed with three of the greatest players of all time. Roger Federer, Rafael Nadal and Novak Djokovic have reigned supreme in men’s tennis for over a decade, but who is the best player out of the three? Read this article to find out what the betting markets suggest.

After Novak Djokovic won his 8th Australian Open and 17th Grand Slam in February this year, I was convinced that 2020 would go a long way to settling the debate about the greatest male player of all time.

Could Federer eek out another slam or two, or would he be caught and ultimately overtaken by Nadal or Djokovic, or both? Tennis has been blessed to have three of the greatest players ever all competing in the same era, but who, once all their careers are said and done, will have the best claim to the greatest of all time (GOAT) tag - Federer, Nadal or Djokovic?

Depending on your perspective, you may think that either one of these three deserves to be the GOAT. Federer hangs on to his lead in both total Grand Slams won with 20 and weeks at the number 1 ranking, Nadal has the best career win/loss record at 83.2% and trails Federer by just one Grand Slam, and yet Djokovic has a superior head-to-head against both of them. 

Even if you think the GOAT debate rests solely on Grand Slam victories, there is a chance that when all their careers are finished, the record will be shared between two or more of Federer, Nadal and Djokovic. In this case, what will settle the debate?

I wanted to cast a different lens over this debate. While Federer, Nadal and Djokovic are undoubtedly three of the greatest players of all time, is there anything more we can learn from looking at how they have been perceived by betting markets, and how they have performed relative to their odds? Let’s take a look at what betting markets can tell us about their careers. Who is the tennis betting GOAT?

Using Grand Slams to assess performance

Beginning with Wimbledon in 2003, where Federer won his first major, only seven players other than Federer, Nadal or Djokovic have won a Grand Slam. Those seven players have won just 11 titles from the past 67 tournaments.

First, I wanted to have a look at whether Federer, Nadal or Djokovic have had the assistance of favourable draws. While comparing the ranking of their opposition is certainly a crude measure, it may indicate whether a player has been consistently lucky at certain stages of tournaments. 

After all, in a slam the winner only needs to defeat seven of the 127 other players, so who you face and in what round could have a decent influence on your chances. The chart below shows the average ranking of Federer, Nadal and Djokovic’s opponents in each round of slams. 


Djokovic has, on balance, played higher ranked opponents in semi-finals and finals, though has had a slightly softer quarter-final draws. Federer’s Grand Slam career got off to a flying start, winning his first seven finals. Amongst these, he defeated players ranked 48, 86 and 54. Djokovic, on the other hand has only faced one player outside the top 10 in his 26 finals appearances.

What do the odds say? 

The next chart plots the players’ average win probabilities implied by their odds. As the purpose was a comparison of the three players, I didn’t remove the margin. We can see that Federer has generally been shorter than both Nadal and Djokovic, although in semi-finals Nadal has had the easiest path, according to the odds. Djokovic has consistently been priced longest of the three. Across semi-finals and finals, Federer’s average odds have been 1.47, Nadal 1.42 and Djokovic 1.56.


On one hand shorter odds may reveal easier draws, although it will also reflect a better player. In a previous article, I showed that tennis betting markets are highly efficient, meaning they offer a great assessment of actual win probabilities. What may be more interesting then, is performance relative to the expectations implied by their odds.

Say Federer is priced at 1.25 for a match. This implies a probability of 1/1.25 = 80%, or 0.8 of a win. If he wins the match, he has won 0.2 of a match above expectation. If he loses, he is 0.8 of a match below expectation. How have Federer, Nadal and Djokovic performed in slams on this measure?


It should be noted that I only had odds data from 2001 onwards, so Federer’s six slam appearances prior to 2001 aren’t included. Pinnacles odds were used from 2004 to 2020. 

In semi-finals and finals, Nadal has performed best of the three, winning 3.6 more matches than betting markets expected him to, despite being priced shorter on average. At +2.8 Djokovic has also performed strongly at the pointy end of slams.

Interestingly, Federer (-1.4) has actually performed below expectation in semi-finals and finals. Across all Grand Slam matches Djokovic is +10.4 matches up on expectation, compared to Nadal +3.4 and Federer +0.5.

Let’s unpack this table a little further and focus on their Grand Slam losses. Federer has lost 53 times at slams (since 2001), Nadal 39 and Djokovic 43. The chart below shows the proportion of these that fall into each implied probability quintile. 


Of their respective losses Federer lost 35 (66%), Nadal 27 (69%), and Djokovic 24 (56%) times as favourite. If we assume Federer’s six slam losses in 1999 and 2000 were more likely to be at longer odds, his percentage will actually be lower than 66%, and it’s fair to say that Nadal has had the highest proportion of unexpected losses at slams.

Similarly, if we look at the average odds in all their losses, Nadal (1.56) just edges Federer (1.58) for the worst record, with Djokovic (1.79) the best. This suggests that in respect to betting market expectations, Nadal has been the least clinical at slams, with Djokovic the most clinical, by some margin.

Who has the most underdog wins?

What about winning as an underdog? While Federer, Nadal and Djokovic haven’t often found themselves as outsiders at a slam, let’s take a look at how they’ve performed when the odds have been against them.  


Djokovic is the only player of the three to have performed better than expected when he’s been an underdog, winning 9 matches from 22, slightly above the 8.1 his expectation. Federer has clearly been the least impressive, winning just 7 from 25 matches, 2.1 less than expected. 

The table below lists the trios’ slam wins as underdog. Djokovic has delivered the biggest upset (4.50 vs Gonzalez at the French Open 2006) and interestingly, Nadal has never beaten Djokovic as an outsider at a slam, in four attempts. He also hasn’t won as an underdog since 2012.


A look at Grand Slam victories in more detail

The knockout structure of a tennis tournament lends itself to a potentially significant ‘luck of the draw’ aspect in results. In a Grand Slam, a player needs to defeat only seven of the other 127 players. When you compare this to other individual sports such as golf, cycling or running, where the winner needs to beat every other participant, it’s clear how influential luck can be.

Fans of Nadal and Djokovic often point to their head-to-head record with Federer as evidence that Federer shouldn’t be considered the GOAT. Can Federer really be the GOAT with a losing record against both his biggest rivals?

Tennis players at the top of the current generation have also benefitted from the move to a 32 seed format, sheltering them from facing the top 32 ranked players until the third round at the earliest. 

Has Federer, Nadal or Djokovic had the easiest path to their titles? The chart below plots the tournament implied probability of each of their victories by multiplying their individual match implied probabilities.

For example, Federer’s most straightforward slam was 2009 Wimbledon where he was never priced longer than 1.11 in his seven matches. His odds were 1.002, 1.005, 1.01, 1.04, 1.07, 1.06 and 1.11, meaning his tournament implied probability worked out to be 75%. By contrast, his 2017 Australian Open title was the hardest fought, overcoming Nadal in the final as a 2.25 outsider to win the title with an 8.9% tournament implied probability. 

Federer (52%) and Nadal’s (49%) median tournament implied probabilities are significantly higher than Djokovic’s (39%) meaning Djokovic has had to work relatively harder for his wins. 


The Grand Slam record race

Djokovic was favourite to close the slam gap further at Wimbledon 2020 before it was cancelled. While Wimbledon recouped some of its lost revenue through its pandemic insurance plan, the chance to win the 2020 event will be lost to history for the players.

Nadal remains the favourite for the 2020 French Open which, at this stage, has been postponed until September. Nadal’s 13th French Open victory would draw him level with Federer on 20 slams. He (33) and Djokovic (32) (both at the time of writing) are considerably younger than Federer (38), and if they can match Federer’s three slam victories after turning 35, they will likely both surpass his slam haul.

How have they performed against expectation?

Using Pinnacle’s closing odds from the beginning of 2004, the chart below tracks the trios’ wins vs. expectation across all their professional matches. Federer performed above expectation early in his career (2004 – 2008) and more recently (2015 – 2020), with a flat period in between.

Nadal made the majority of gains vs. expectation from 2004 to 2009 and has performed in line since. Djokovic’s trajectory shows a sustained decade of outperformance from 2006 to 2016 followed by a flatter period, which coincided with Federer and Nadal’s resurgence.

Overall Djokovic has performed best of the three compared to expectation. He sits at +36 wins above expectation compared to Federer +26, and Nadal +18. If slam performances are removed, Djokovic (+25) and Federer (+25) have an identical record, though both are significantly better than Nadal’s (+15).


Who comes out on top in head-to-heads?

Fans of Nadal and Djokovic often point to their head-to-head record with Federer as evidence that Federer shouldn’t be considered the GOAT. Can Federer really be the GOAT with a losing record against both his biggest rivals? Federer’s record against Djokovic is 23-27 and against Nadal is 16-24.

Let’s dig a little deeper. In total, 40% of Federer and Nadal’s clashes have taken place on clay, where Nadal is undoubtedly superior (Nadal leads 14-2). On hard and grass courts it’s a different match up, with Federer ahead 12-9 and 3-1 respectively. Their head-to-head probably flatters Nadal due to the higher proportion of clay matches the pair have played. If they had played more on grass, I’m certain Federer would have been closer at worst. 

Interestingly, Federer (-1.4) has actually performed below expectation in semi-finals and finals. Across all Grand Slam matches Djokovic is +10.4 matches up on expectation, compared to Nadal +3.4 and Federer +0.5.

Djokovic, on the other hand, has a winning record against Federer on both hard (20-18) and grass courts (3-1), while they have split their eight meetings on clay. Djokovic has also fared better than Federer on clay against Nadal (7-16) and has a more dominant hard-court record against the Spaniard (20-7).

Djokovic and Nadal have split their four grass meetings, for a 29-26 head-to-head in favour of Djokovic. So, Djokovic leads both his Federer and Nadal matchup. However, analysing whether these records are expected based on the odds will provide us with a bit more detail.

Federer vs. Nadal

Nadal has started favourite 23 times (including 14 of 16 on clay) from his 40 matches with Federer. Calculated from Pinnacles closing odds, Nadal was expected to win 20.8 and Federer 19.2, meaning Nadal’s 24 wins puts him 3.2 wins above expectation.

By Plotting their expected and total wins in the chart below, we can see that Federer had been consistently overvalued. Before Federer’s win in the 2015 Basel final he was six wins below expectation. Only a six-match winning streak, which ended at the 2019 French Open, closed the expectation gap somewhat for Federer, yet he remains at a decent deficit to Nadal in both wins and wins vs. expectation.


Nadal vs. Djokovic

Across their 55 matches, Nadal has started favourite on 33 occasions, Djokovic 22. We can see from the chart below that Nadal has performed significantly worse than Pinnacle’s closing odds implied, winning just 26 games from an expected 31.2.

On the other hand, Djokovic sits 5.2 matches above expectation at 29 wins (compared to an expected 23.8). This match up first began to diverge from expectation in 2011, when Djokovic went on a seven-match winning streak, and has continued to widen in Djokovic’s favour since. Since the 2011 Indian Wells final, Djokovic has won 22 from 32 matches against Nadal.


Djokovic vs. Federer

There have been two distinct periods in the Djokovic vs. Federer rivalry. In the pairs’ 19 matches prior to 2011, Federer started favourite on 18 occasions, winning 13. In the 31 matches since, Federer only started favourite four times, and won 10.

Overall, the odds give Djokovic a slight expectation edge, with 25.1 expected match wins to Federer’s 24.9. The match up has played out relatively close to this expectation, with neither player ever in excess of three matches above expectation. Following Djokovic’s victory in the 2020 Australian Open semi-finals, Djokovic’s 27-23 record has him 1.9 matches above expectation for the match up.


Who is the tennis GOAT?

For me, as much as I love watching Federer play, and admire Nadal’s mental fortitude, it seems like Djokovic is probably on track to surpass them both. With Wimbledon cancelled this year, and being 39 years of age by the time the next slam is contested, I struggle to see Federer winning another major.

Nadal is favourite to equal Federer on 20 slams at this year’s French Open, though Djokovic will too be eager to claim his second French title, and will hold fond memories of beating Nadal at their most recent encounter at the tournament in 2015.

Notwithstanding injury, Djokovic should be favourite for the three non-clay slams for the foreseeable future, and on his form from the last few years should be good enough to claim the slam record.

The title of the betting GOAT is a little more clear-cut. Djokovic holds the advantage on almost every measure. He has had more difficult slam draws than Federer and Nadal, and yet performed significantly better than expectation as both a favourite and an underdog.

He has been the most clinical in victory, outperformed expectation in both key matchups and more broadly across his entire career. Djokovic is the undisputed tennis betting GOAT. Whether he surpasses his rivals with slams, and in the eyes of tennis fans remains to be seen.

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