Martina Hingis (born 30 September 1980) is a retired Swiss professional tennis player who spent a total of 209 weeks as World No. 1. She won five Grand Slam singles titles (three Australian Opens, one Wimbledon, and one US Open). She also won nine Grand Slam women's doubles titles, winning a calendar year doubles Grand Slam in 1998, and one Grand Slam mixed doubles title.

Hingis set a series of "youngest-ever" records before ligament injuries in both ankles forced her to withdraw temporarily from professional tennis in 2002 at the age of 22. After several surgeries and long recuperations, Hingis returned to the WTA tour in 2006. She then climbed to world number 6 and won three singles titles. On 1 November 2007, Hingis announced her retirement from tennis after testing positive for cocaine during Wimbledon in 2007. She denied using the drug, but decided not to appeal the imminent ban.

In June 2011, she was named one of the "30 Legends of Women's Tennis: Past, Present and Future" by Time.

Hingis was born in Košice, (then part of Czechoslovakia, now in modern Slovakia), to accomplished tennis players Melanie Molitorová and Karol Hingis. Molitorová was a professional tennis player, who was once ranked tenth among women in Czechoslovakia, and was determined to develop Hingis into a top player as early as pregnancy. Her father was ranked as high as nineteenth in the Czechoslovakian tennis rankings. Hingis's parents divorced when she was six, and she and her mother relocated around a year later to Trübbach in Switzerland. Her father, who continued to live in Košice as a tennis coach, said in 1997 that he had seen little of his daughter after the split.

Serena Jameka Williams (born September 26, 1981) is an American professional tennis player and a former world no. 1. The Women's Tennis Association has ranked her world no. 1 in singles on five separate occasions. She became the world no. 1 for the first time on July 8, 2002 and regained this ranking for the fifth time on November 2, 2009. She is the only female player to have won over $35 million in prize money.

Her 27 Grand Slam titles places her ninth on the all-time list: 13 in singles, 12 in women's doubles, and 2 in mixed doubles. She is the most recent player, male or female, to have held all four Grand Slam singles titles simultaneously and only the fifth woman in history to do so. She was also the first woman, along with sister Venus Williams, to hold all four Grand Slam doubles titles simultaneously since Martina Hingis did so in 1998. Her 13 Grand Slam singles titles is sixth on the all-time list. Williams ranks fourth in Grand Slam women's singles titles won during the open era, behind Steffi Graf (22 titles) and Chris Evert and Martina Navratilova (18 titles each). She has won more Major titles in singles, doubles, and mixed doubles than any other active player, male or female.

Anna Sergeyevna Kournikova (Russian:  Анна Сергеевна Ку́рникова; born 7 June 1981) is a Russian retired professional tennis player. Her beauty and celebrity status made her one of the best known tennis stars worldwide, despite her never winning a WTA singles title. At the peak of her fame, fans looking for images of Kournikova made her name one of the most common search strings on Google.

Although reaching No. 8 in the world in 2000, she never won a WTA Title in singles. Kournikova's forte has been doubles, where she has 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. Based on their looks, Hingis and Kournikova referred to themselves as the "Spice Girls of Tennis".

Kournikova's professional tennis career has been curtailed, and possibly ended, by serious back and spinal problems in the past several years. She resides 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 will 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.