No doubt that singles is the main aim for most players. However, the bottom line is money. This means doubles. Give singles your best shot for another year or two. After that include doubles (men's n mixed) and try to emulate the Woodies and our own Paes n Bhoops. Make it a point to study both teams game plus career earnings, year by year, age by age. Being Indian does make one emotional but winning the big ones with, even Sania, would be cloud 9. All the best.
