Question: Who was India's No. 1 player in both singles and doubles before their retirement, Frederik Nielsen or Sania Mirza?

Context articles: Mervana Jugić-Salkić
Sania Mirza
Vishnu Vardhan
Tennis at the 2010 Asian Games – Mixed doubles
Olivia Rogowska
2012 Wimbledon Championships – Men's Doubles
2016 Apia International Sydney – Women's Doubles
Frederik Nielsen
Tennis at the 2006 Asian Games – Mixed doubles
2017 St. Petersburg Ladies' Trophy – Doubles

Mervana Jugić-Salkić (born 14 May 1980) is a Bosnian former tennis player.
 She turned professional in 1999, and reached her highest singles ranking on 21 June 2004, when she was ranked World No. 99.
 On 10 July 2006, Jugić-Salkić reached No. 59 in doubles, after winning ASB Classic in 2004 with Jelena Kostanić and Internazionali di Modena in 2005 with Yuliya Beygelzimer.
 She also won 15 singles and 43 doubles events organized by International Tennis Federation.
 Jugić-Salkić represented Bosnia and Herzegovina at the 2004 Summer Olympics, but fell to Maria Elena Camerin in the first round.
 During her long career, she defeated players such as Yan Zi, Victoria Azarenka, Bethanie Mattek, Sania Mirza, Anabel Medina Garrigues, Nuria Llagostera Vives and Sybille Bammer.
Sania Mirza (] ; born 15 November 1986) is an Indian professional tennis player who was formerly ranked No. 1 in the women's doubles rankings.
 From 2003 until her retirement from singles in 2013, she was ranked by the Women's Tennis Association as India's No. 1 player, both in singles and doubles.
 Throughout her career, Mirza has established herself as the most successful female Indian tennis player ever and one of the highest-paid and high-profile athletes in the country.
Vishnu Vardhan (born 27 July 1987), also known as J. Vishnuvardhan, is a professional tennis player from India, ranked in the top 300 on the ATP Tour as of 9 July 2012.
 He was a member of the bronze medalist Indian men's team for 2010 Asian games in Guangzhou, China.
 He paired-up with and Sania Mirza for mixed doubles and won silver medal.
 He won the national singles title for the fourth time by winning the Men's final of Fenesta Open tennis Championship on October 8, 2016
At the 2010 Asian Games in the Mixed doubles tennis event, Sania Mirza and Leander Paes were the defending champions, but only Mirza participated, as Paes was involved in the Tour Finals.
 Mirza partnered up with Vishnu Vardhan.
 They went on to win the silver medal after losing to Chan Yung-jan and Yang Tsung-hua in the final 6–4, 1–6, [2–10].
Olivia Rogowska (born 7 June 1991) is an Australian professional tennis player.
 Both of her parents are Polish.
 The right-hander was born in and lives in Melbourne, Australia.
 Her highest WTA singles ranking is 102, which she reached on 11 August 2014.
 Her career high in doubles is 89, which she reached on 28 July 2014.
 She has defeated Jelena Dokić, Alicia Molik, Maria Kirilenko and Sofia Arvidsson, and taken sets from former #1 Dinara Safina, Alona Bondarenko, Kateryna Bondarenko, Sorana Cîrstea, Jarmila Gajdošová, Anastasia Rodionova, Sania Mirza and Casey Dellacqua.
Bob Bryan and Mike Bryan were the defending champions, but lost to wildcards Jonathan Marray and Frederik Nielsen in the semifinals.
 Marray and Nielsen won the title defeating fifth seeded Robert Lindstedt and Horia Tecău who competed in their third consecutive Wimbledon final.
 Marray became the first British player to win the men's doubles at Wimbledon since Pat Hughes and Raymond Tuckey in 1936.
 Nielsen is only the second Danish winner of a Grand Slam title, following his own grandfather, Kurt Nielsen, who won the mixed doubles at the 1957 U.S. National Championships.
Bethanie Mattek-Sands and Sania Mirza were the defending champions, but Mattek-Sands chose not to participate this year.
 Mirza played alongside Martina Hingis and successfully defended her title, defeating Caroline Garcia and Kristina Mladenovic in the final, 1–6, 7–5, [10–5].
Frederik Løchte Nielsen (born 27 August 1983) is a professional male tennis player.
 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.
 Nielsen is coached by fellow Dane John Larsen and is a member of the Denmark Davis Cup team.
 His grandfather is former grand slam finalist Kurt Nielsen.
Mixed doubles at the 2006 Asian Games was won by Sania Mirza and Leander Paes of India.
Martina Hingis and Sania Mirza were the defending champions, but Mirza chose not to participate this year.
 Hingis played alongside Belinda Bencic, but lost in the first round to Gabriela Dabrowski and Michaëlla Krajicek.