As of December 31st, 2020, the average age in the ATP top 20 was 28.7. Roughly half of the players – 9 to be exact – have celebrated their 30th birthday; Roger Federer, Rafael Nadal, Stan Wawrinka, Gael Monfils, and others, have been mainstays in the second weeks of Grand Slams for over a decade. But how did these elite players get to the top of our sport in the first place? Specifically, how highly ranked were they as juniors? And after turning pro, how old were they when they first ranked inside the ATP top 100? How about the top 50, and finally top 20?
To do that, I have decided to look at the 20 highest ranked players in the final rankings for the years 2016 – 2020. During that period, 38 individual players have finished the year inside the top 20 in any given year. (Note that someone like, say, Felix Auger-Aliassime is not included in the dataset; while has has already been ranked inside the top 20, he hasn’t finished the year ranked as high just yet).
The raw data is presented below. While the column names are self-explanatory, I have decided to split the individual ages for a bit more granularity. For example, let’s say a particular player’s birthday is in May, and he cracks the top 100 in August of the year he turns 20. His value in the table would have been 20.25, indicating 20 years old “an a quarter.” This was done to differentiate players who achieve a certain milestone, let’s say, the day after their 19th birthday, as opposed to someone who achieves that same milestone at age 19 and 10 months. The players are listed in alphabetical order by last name.
2016 – 2020 EOY ATP Top 20
| Name | Career High ITF Junior Ranking | ATP Top 100 Break Age | ATP Top 50 Break Age | ATP Top 20 Break Age |
| Anderson | 28 | 22 | 24.75 | 27.25 |
| Bautista Agut | 47 | 24.25 | 25.25 | 26.25 |
| Berdych | 6 | 18.5 | 19 | 20.75 |
| Berrettini | 52 | 22 | 22.75 | 23.25 |
| Carreno Busta | 6 | 22 | 23.25 | 25.75 |
| Cecchinato | 100 | 22.75 | 25.75 | 26 |
| Cilic | 1 | 19 | 19.25 | 20.25 |
| Coric | 1 | 18 | 18.5 | 21.75 |
| De Minaur | 2 | 19.25 | 19.5 | 20.75 |
| Del Potro | 3 | 18 | 19 | 20 |
| Dimitrov | 1 | 19.75 | 21.5 | 22.75 |
| Djokovic | 24 | 18.25 | 19 | 19.25 |
| Edmund | 8 | 20.5 | 21.75 | 23.25 |
| Federer | 1 | 18 | 18.5 | 19.5 |
| Fognini | 8 | 20.5 | 24 | 26.25 |
| Gasquet | 1 | 17.25 | 19 | 19 |
| Goffin | 10 | 21.5 | 21.75 | 24.25 |
| Isner | 93 | 22.75 | 24.5 | 24.75 |
| Karlovic | N/A | 24.5 | 27.25 | 29 |
| Khachanov | 16 | 20 | 20.75 | 22.5 |
| Kyrgios | 1 | 19.25 | 19.75 | 21 |
| Medvedev | 13 | 20.75 | 21.5 | 22.75 |
| Monfils | 1 | 18.75 | 19 | 22 |
| Murray | 2 | 18.5 | 18.75 | 19.25 |
| Nadal | 145 | 16.75 | 17.25 | 18.75 |
| Nishikori | 7 | 18.25 | 21.25 | 22 |
| Pouille | 23 | 21.25 | 22.25 | 22.5 |
| Querrey | 10 | 19.25 | 19.75 | 22.75 |
| Raonic | 35 | 20 | 20.25 | 21.75 |
| Rublev | 1 | 19.75 | 20 | 22.25 |
| Schwartzman | 217 | 21.75 | 24.5 | 25.5 |
| Shapovalov | 2 | 18.25 | 18.5 | 20 |
| Sock | 22 | 20.75 | 22 | 24.25 |
| Thiem | 2 | 20.5 | 20.75 | 22 |
| Tsitsipas | 1 | 19.25 | 19.5 | 20 |
| Tsonga | 2 | 22.25 | 22.5 | 22.75 |
| Wawrinka | 7 | 20 | 20.75 | 23.25 |
| Zverev | 1 | 18 | 19 | 19.5 |
| Mean | 20.05 | 21.11 | 22.49 | |
| Median | 19.875 | 20.75 | 22.375 | |
| Min | 16.75 | 17.25 | 18.75 | |
| Max | 24.5 | 27.25 | 29 |
There are three general takeaways from looking at the group as a whole:
High junior ranking
Out of the 38 players in the sample, 35 have been ranked inside the top 100 world junior rankings during the early stages of their tennis careers. The only exceptions are Ivo Karlovic, Diego Schwartzman, and Rafael Nadal. However, Rafael Nadal was already ranked inside the top 50 ATP by the time he turned 18 years old.
Moreover, 10 of the 38 players have been ranked #1 in the world as a junior, with 14 additional players having been ranked inside the top 10. That’s 24 out of the 38, or about 63% ranked higher that #10 ITF. A better than a top 100 junior ranking looks almost like a prerequisite to eventually make the ATP top 20, i.e these players have shown their potential in the junior ranks already.
Quick ascent into top 100
With most of these players having been elite juniors, they broke into the ATP top 100, on average, at around 20 years old. In other words, they tend to spend only about two years competing in the smaller tournaments on the Futures and Challenger circuits. Rafael Nadal was the youngest one in the sample, at less than 17 years old, while the oldest was Ivo Karlovic at over 24 years of age.
Slower ascent into top 20
As these players cracked the top 100 at around the age of 20, they first got into the top 50 roughly a year later, around the age of 21. The last thirty spots, into the top 20, then took about another year and a half, and the average age of cracking the top 20 was about 22.5. Once a player establishes himself in the top 20, he gets every opportunity – baring injury – to stay there, by being seeded at every tournament he plays and evading fellow top 20 players until the later rounds of a tournament. That is the main reason why the average age of the top 20 players in the world is significantly higher than the average age of the players breaking in for the first time: over the past five years at least, the players who make it into the top 20 tend to stay there.
While general observations are certainly useful, let’s see if we can learn some additional information by splitting the group of 38 players further. I have decided to do the split according to the highest achieved ITF junior ranking, and came up with the following three groups:
- Players, who have achieved the #1 world ranking as juniors (10 players)
- Players, who were ranked between #2 – #10 in the world as juniors (14 players)
- Everyone else (14 players)
#1 ITF
| Name | Career High ITF Junior Ranking | ATP Top 100 Break Age | ATP Top 50 Break Age | ATP Top 20 Break Age |
| Cilic | 1 | 19 | 19.25 | 20.25 |
| Coric | 1 | 18 | 18.5 | 21.75 |
| Dimitrov | 1 | 19.75 | 21.5 | 22.75 |
| Federer | 1 | 18 | 18.5 | 19.5 |
| Gasquet | 1 | 17.25 | 19 | 19 |
| Kyrgios | 1 | 19.25 | 19.75 | 21 |
| Monfils | 1 | 18.75 | 19 | 22 |
| Rublev | 1 | 19.75 | 20 | 22.25 |
| Tsitsipas | 1 | 19.25 | 19.5 | 20 |
| Zverev | 1 | 18 | 19 | 19.5 |
| Mean | 18.7 | 19.4 | 20.8 | |
| Median | 18.875 | 19.125 | 20.625 | |
| Min | 17.25 | 18.5 | 19 | |
| Max | 19.75 | 21.5 | 22.75 |
Not only has everyone on this list been ranked #1 ITF; every player on this list has won a junior Grand Slam title as well. In other words, these players would be everyone’s first choice in predicting the future stars of men’s tennis.
The #1 ranked juniors broke into the top 100 a year earlier than the whole group – 18.7 as opposed to 20.05. In fact, these guys tended to break into the top 50 by the time the rest of the group broke into the top 100. Interestingly enough, the pattern of a slower ascent into the top 20 holds for these players too: on average, it took them roughly 8 months (0.7 years) to make the jump from top 100 to top 50, but then another 17 months (1.4 years) to progress from top 50 to top 20.
If I was going to pick an upcoming member of this group, it would be the young Italian Lorenzo Musetti. Musetti has been ranked #1 ITF, he has won the 2019 Australian Open juniors crown, is currently ranked #129 ATP and doesn’t turn 19 until March 2021.
#2 – #10 ITF
| Name | Career High ITF Junior Ranking | ATP Top 100 Break Age | ATP Top 50 Break Age | ATP Top 20 Break Age |
| Berdych | 6 | 18.5 | 19 | 20.75 |
| Carreno Busta | 6 | 22 | 23.25 | 25.75 |
| De Minaur | 2 | 19.25 | 19.5 | 20.75 |
| Del Potro | 3 | 18 | 19 | 20 |
| Edmund | 8 | 20.5 | 21.75 | 23.25 |
| Fognini | 8 | 20.5 | 24 | 26.25 |
| Goffin | 10 | 21.5 | 21.75 | 24.25 |
| Murray | 2 | 18.5 | 18.75 | 19.25 |
| Nishikori | 7 | 18.25 | 21.25 | 22 |
| Querrey | 10 | 19.25 | 19.75 | 22.75 |
| Shapovalov | 2 | 18.25 | 18.5 | 20 |
| Thiem | 2 | 20.5 | 20.75 | 22 |
| Tsonga | 2 | 22.25 | 22.5 | 22.75 |
| Wawrinka | 7 | 20 | 20.75 | 23.25 |
| Mean | 19.80 | 20.75 | 22.36 | |
| Median | 19.625 | 20.75 | 22.375 | |
| Min | 18 | 18.5 | 19.25 | |
| Max | 22.25 | 23.25 | 26.25 |
This group most closely follows the pattern of the whole sample, i.e. top 100 right around 20, top 50 around 21, and top 20 around 22.5 years old. On the other hand, there is a lot of variability within the group itself. We have players like Andy Murray, who have made it to the top 20 before their 20th birthday, while we also have someone like Fabio Fognini, who didn’t achieve that ranking until after he was 26 years old.
I want to point out two differences between this group, and the group of players who have achieved the #1 junior ranking. First, the #1 group, on average, made the jump into the ATP top 100 a full year younger than the #2 – #10 group. Also, while it took the #1 group less than a year to crack the top 50 after first making it to the top 100, it took the #2 – #10 group almost a full year. Admittedly, the sample size is not very big, yet the ascent up the professional ranks seemed to slow down a little bit for the #2 – #10 group.
My pick for the next member of this group is Thiago Seyboth Wild from Brazil. Thiago is currently ranked #117 ATP, was ranked as high as #8 in the world as a junior, and he will turn 21 in March of 2021.
Outside Top 10 ITF
| Name | Career High ITF Junior Ranking | ATP Top 100 Break Age | ATP Top 50 Break Age | ATP Top 20 Break Age |
| Anderson | 28 | 22 | 24.75 | 27.25 |
| Bautista Agut | 47 | 24.25 | 25.25 | 26.25 |
| Berrettini | 52 | 22 | 22.75 | 23.25 |
| Cecchinato | 100 | 22.75 | 25.75 | 26 |
| Djokovic | 24 | 18.25 | 19 | 19.25 |
| Isner | 93 | 22.75 | 24.5 | 24.75 |
| Karlovic | N/A | 24.5 | 27.25 | 29 |
| Khachanov | 16 | 20 | 20.75 | 22.5 |
| Medvedev | 13 | 20.75 | 21.5 | 22.75 |
| Nadal | 145 | 16.75 | 17.25 | 18.75 |
| Pouille | 23 | 21.25 | 22.25 | 22.5 |
| Raonic | 35 | 20 | 20.25 | 21.75 |
| Schwartzman | 217 | 21.75 | 24.5 | 25.5 |
| Sock | 22 | 20.75 | 22 | 24.25 |
| Mean | 21.27 | 22.70 | 23.84 | |
| Mean (no Nadal) | 21.62 | 23.12 | 24.23 | |
| Median | 21.5 | 22.5 | 23.75 | |
| Median (no Nadal) | 21.75 | 22.75 | 24.25 | |
| Min | 16.75 | 17.25 | 18.75 | |
| Min (no Nadal) | 18.25 | 19 | 19.25 | |
| Max | 24.5 | 27.25 | 29 |
This is the most varied group of the set. It includes players, who went to play NCAA Division 1 tennis after their junior careers, in John Isner and Kevin Anderson. It includes two of the best players of all time in Novak Djokovic and Rafael Nadal. It also includes Ivo Karlovic and Diego Schwartzman – really as polar opposites as you can get in terms of physical stature, as well as game style.
I have decided to calculate the statistics twice for this group: once with Rafael Nadal, and once without him. As he often is in tennis, Nadal is an extreme outlier, and could skew the data a little bit. I think that the statistics without Nadal are a little more informative.
Without Rafael Nadal, players in this group tended to break into the top 100, on average, after their 21st birthday, and into the top 20 around the age of 24. Compared to the #1 ranked juniors, their developments took roughly three years longer in both instances. Compared to the #2 – #10 group, their rankings progression was roughly two years slower.
I would guess that the main reason for this is – apart from the quality of the players – that players ranked outside of the top 10 ITF are less attractive for sponsors and agents, and are often not afforded the luxury of multiple wild cards into main draws of challengers or ATP tournaments. These guys have to earn their ranking “the hard way,” working their way through qualifying events at the Futures and Challenger levels. It takes a certain level of physical and mental maturity to be able to win multiple matches in a qualifying draw before even being afforded the opportunity to compete for ATP points in the main draw of a tournament. Junior and professional tennis are really two different worlds, and the adjustment to the pro game takes some time for the vast majority of players.
Takeaways
While I don’t think we can make sweeping generalizations based on this data alone, I think it contains some nuggets that we can keep in mind when looking for the next big star.
If you’re a young player, and your goal is to be in the top 20 in the world as a professional, a necessary first step is to achieve a top 100 junior ranking as a bare minimum; top 10 is really what you should be shooting for.
If you’re a tennis federation with a junior player ranked between #10 – #100 in the world, understand that he might not crack the top 100 for four or five years after his junior career is over. In other words, be prepared to support him for longer than one or two years, if you really believe in the player’s potential. Otherwise you run the risk of giving up too quickly.
Similarly, if you’re a parent of a player ranked between #10 – #100 ITF, and have the financial means to support your son for a year and then “see how it goes,” understand that your son is not likely to be in the top 100 after one year of professional tennis. It will be a longer process.
Finally, if you’re a fan and want to know the “next big thing” before the rest of your friends do, then pick a player, who has been recently ranked #1 in the world as a junior, and won a junior Grand Slam title. In about a year, your friends might be impressed.
Michal's Musings 
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