Who was India's No. 1 player in both singles and doubles before their retirement, Frederik Nielsen or Sania Mirza?
Frederik Nielsen:  He is a former Wimbledon Men's Doubles champion, in 2012, and now competes mainly on the ATP Challenger Tour in both singles and doubles. Sania Mirza: Sania Mirza (] ; born 15 November 1986) is an Indian professional tennis player who was formerly ranked No. 1 in the women's doubles rankings.
i don't know