I dont understand your question as to in what context it is asked or related. Li Na of China is the sixth seed today in world's women's tennis rankings and she has gone as high as No. 3. She has already won the French Open Grand Slam in singles and this was her second Australian Open Final.
As regards Sania Mirza, in singles I think her current world ranking is not even in the top 100. Her highest singles ranking till date has been 30 and she has never progressed beyond the fourth round in singles in Grand Slams. In fact in singles I think she has never beaten a top 10 ranked player ever in any tournament. The reasons for that are obvious, that she is not a good tennis player and the Indian media has always given her more publicity then she deserved. And of late she is concentrating and playing more in the doubles - both womens and mixed doubles. She has won two mixed doubles Grand Slams pairing with Mahesh Bhupati. But the top singles players of both men and women hardly play double ...more

Not in top circuit