Countries with most successful tennis players in the world

Nowadays US open tennis tournament is going on.

 Here I am listing out the countries having top tennis players   ----

1.   United States of America

2.  Australia 

3.  Great Britain 

4.  Switzerland 

5.  Spain 

6.  Serbia 

7.   Sweden 

8.  France 

9.  Czech Republic 

10.   Russia