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.

Caroline Wozniacki (born 11 July 1990) is a Danish professional tennis player. She is a former world no. 1 on the WTA Tour. As of 23 January 2012, she held this position for 67 weeks. She is the first Scandinavian woman to hold the top ranking position and 20th overall.

Since her WTA debut in 2005, she has improved her year-end ranking each year until finishing on top in both 2010 and 2011. She has won 18 WTA singles titles as of August 2011, three in 2008, three in 2009, six in 2010 (the most since Justine Henin's ten in 2007), and six in 2011. She was runner-up at the 2009 US Open and the 2010 WTA Tour Championships in Doha to Kim Clijsters. She won the 2006 Wimbledon Girls' Singles title but has yet to win a women's Grand Slam title. She also holds two WTA titles in doubles.

Wozniacki is the daughter of Polish Roman Catholicimmigrants, Piotr and Anna Wozniacki. Anna played on the Polish women's national volleyball team, and Piotr played professional football. The couple moved to Denmark when Piotr signed for the Danish football club Boldklubben 1909. Wozniacki's older brother Patrik Wozniacki is a professional footballer for Hvidovre IF in Denmark.

Maria Yuryevna Sharapova (Russian: Мария Юрьевна Шарапова [mɐˈrʲijə ˈjurʲjɪvnə ʂɐˈrapəvə] ( listen), US: /ʃɑrəˈpoʊvə/, UK: /ʃærəˈpoʊvə/; born April 19, 1987) is a Russian professional tennis player and former world no. 1. A United States resident since 1994, Sharapova has won 26 WTA singles titles, including three Grand Slam singles titles at the 2004 Wimbledon, 2006 US Open and 2008 Australian Open. She has also won the year-end WTA Tour Championships in 2004. The Women's Tennis Association has ranked Sharapova world no. 1 in singles on four separate occasions. She became the world no. 1 for the first time on August 22, 2005, and last regained the ranking for the fourth time on May 19, 2008. As of May 28, 2012, Sharapova is ranked world no. 2. She has been in six Grand Slam finals with the final record 3–3.

Sharapova made her professional breakthrough in 2004 at age 17, when she defeated two-time defending champion and top seed Serena Williams in the 2004 Wimbledon final for her first Grand Slam singles title. She entered the top 10 of the WTA Rankings with the win. Despite not winning a major in 2005, Sharapova briefly held the no. 1 ranking, and reached three Grand Slam semifinals, losing to the eventual champion each time. She won her second major at the 2006 US Open defeating then-world no. 1 Amélie Mauresmo in the semifinals and world no. 2 Justine Henin in the final.