The 2003 WTA Tour Championships, also known by its sponsored name Bank of America WTA Tour Championships Presented by Porsche, was a women's tennis tournament played on indoor hard courts at the Staples Center in Los Angeles, United States. It was the 33rd edition of the year-end singles championships, the 28th edition of the year-end doubles championships, and was part of the 2003 WTA Tour. The tournament was held between November 4 and November 10, 2003. First-seeded Kim Clijsters won the singles event and earned $1,000,030 first-prize money as well as 485 ranking points.[1] With her victory Clijsters became the first female tennis player to earn $US4 million in a season.[2] For the first time since 1978 a round robin system was used, after the men's Tennis Masters Cup. Two groups of four players were formed and each contender had to play three matches.[3] Also, for singles, instead of the top sixteen players qualifying, only top eight qualified for the WTA Tour Championships. For doubles, the top four pairs (previously top eight) pairs qualified for the WTA Tour Championships, but still continued with the single elimination format.
See main article: 2003 WTA Tour Championships – Singles. 
Kim Clijsters defeated 
Amélie Mauresmo, 6–2, 6–0.
See main article: 2003 WTA Tour Championships – Doubles. 
Virginia Ruano Pascual / 
Paola Suárez defeated Kim Clijsters / 
Ai Sugiyama, 6–4, 3–6, 6–3.