For professional tennis players, the choice between becoming a singles player or a doubles player is an important issue. In my research so far, players can be classified into "precocious" and "late-blooming" types based on whether the men's singles world ranking is ranked 100th at the age of 20. The purpose of this study is to help young players build their careers by clarifying their limits as a singles player and their potential as a doubles player at the age of 20.
Doubles players receive the same or higher prize money than singles players if they have the same ranking at the age of 20. In addition, it is difficult for singles players to rank 100th in the singles ranking if they have not reached the 300th rank at the age of 20. However, even if the doubles players are ranked 701 to 900 at the age of 20, more than half of the players can be ranked 100th in the doubles ranking. The prize money earned by compatible players who participated in both singles and doubles games (about 50% each) was lower than that of doubles players.