Stefan Edberg was the defending champion but lost in the second round to Karel Novacek.
Sixteen-year old Lleyton Hewitt defeated Jason Stoltenberg 3–6, 6–3, 7–6(7–4) to secure the title.
First-seeded Marcelo Ríos defeated Richard Fromberg 4–6, 6–4, 7–6(7–3) to win the 1998 Heineken Open singles competition. Jonas Björkman was the champion but did not defend his title.
Thomas Enqvist defeated Yevgeny Kafelnikov 6–4, 6–1 to win the 1998 Open 13 singles competition. Enqvist was the defending champion.
Mark Philippoussis was the defending champion, but lost in the second round this year.
Mark Philippoussis was the defending champion, but lost in the second round this year.
Thomas Muster was the defending champion and won in the final 6–2, 6–4, 3–6, 6–3 against Richard Krajicek.
Andriy Medvedev was the defending champion but lost in the second round to Jordi Burillo.
The 1999 Open Gaz de France – Singles was the singles event of the seventh edition of the Open GDF Suez; a WTA Tier II tournament held in Paris, France. Mary Pierce was the defending champion but did not compete that year.
The 1999 Lipton Championships – Women's Singles was the women's singles event of the fifteenth edition of the tennis tournament played at Miami, United States. It is the third WTA Tier I tournament of the year, and part of the US Spring tennis season. Venus Williams was the defending champion, and she successfully defending her title by defeating her sister Serena in the final 6–1, 4–6, 6–4.
The 1999 Australian Open – Mixed Doubles was the mixed doubles event of the eighty-seventh edition of the Australian Open, the first Grand Slam of the year. Venus Williams and Justin Gimelstob were the defending champions but did not compete that year.
Katarina Srebotnik and Nenad Zimonjić were the defending champions but lost to Casey Dellacqua and Scott Lipsky in the final 7–6(8–6),4–6,[10–7]. This was the only major championship won by either Dellacqua or Lipsky in their careers.
Yevgeny Kafelnikov was the defending champion and defended his title with 6–4, 6–4 against Magnus Larsson.
The 1999 DFS Classic – Singles was the singles event of the seventeenth edition of the Aegon Classic, a WTA Tier III tournament held in Birmingham, England, United Kingdom and part of the European grass court season. There was no defending champion in 1999 due to the cancellation of the 1998 final as a result of rain.
Jonas Björkman was the defending champion, but lost in the second round this year.
The 1999 Orange Prokom Open – Singles was the singles event of the second edition of the most prestigious women's tennis tournament held in Poland. Henrieta Nagyová was the defending champion, and the sixth seed this year, but she retired 2–6, 1–4 down against Silvija Talaja.
The 2013 BNP Paribas Open – Men's Singles was the main event of the 2013 BNP Paribas Open men's tennis tournament played in Indian Wells, USA from March 7 through March 17, 2013.
The 1999 Wismilak International – Singles was the singles event of the fifth edition of the most prestigious women's tennis tournament held in Southeast Asia. It was not played the previous year, so there was no defending champion.
Martina Hingis and Leander Paes were the defending champions, but lost in the second round to Coco Vandeweghe and Rajeev Ram.
Łukasz Kubot and Marcelo Melo were the defending champions, but lost in the first round to Steve Johnson and Sam Querrey.
