Although reaching No. 8 in the world in 2000, she never won a WTA Title in singles. Kournikova achieved greater success playing doubles, where she had at times been the World No. 1 player. With Martina Hingis as her partner, she won Grand Slam titles in Australia in 1999 and 2002. The doubles team referred to themselves as the "Spice Girls of Tennis".
Kournikova's professional tennis career ended prematurely at the age of 21 due to serious back and spinal problems, including a herniated disk. She lives in Miami Beach, Florida, and plays in occasional exhibitions and in doubles for the St. Louis Aces of World Team Tennis. She was a new trainer for season 12 of the television show The Biggest Loser, replacing Jillian Michaels, but did not return for season 13. In addition to her tennis and television work, Kournikova serves as a Global Ambassador for Population Services International's Five & Alive program, which addresses health crises facing children under the age of five and their families.
