Halfway through the year, there are many teams still in contention for the four spots that will make up the doubles field at the season-ending Sony Ericsson Championships - Doha 2009.

Cara Black and Liezel Huber, the two-time defending champions, have a strong hold on the No.1 position. Although they have not captured a Grand Slam in 2009, they have a Sony Ericsson WTA Tour-leading four titles at Paris [Indoors], Dubai, Madrid and Birmingham. They have also made the semis at four events, including Roland Garros and Wimbledon, and the quarters at four, including the Australian Open.

Serena and Venus Williams have not played in any tournaments besides the three Grand Slams. However, capturing two of them - the Australian Open and Wimbledon - has put them in second place in the standings. They have never previously played in the season-ending doubles event, but look on track to make their first appearance in it this year.

Spaniards Anabel Medina Garrigues and Virginia Ruano Pascual occupy third place. They have only won one event this year, but it was a big one, Roland Garros. They also picked up a lot of points by being finalists in Marbella, semifinalists at Wimbledon and quarterfinalists in Miami. In their only previous appearance at this event, they lost in the semis last year to Black and Huber.

Australians Samantha Stosur and Rennae Stubbs, in fourth place, aren't far behind Medina Garrigues and Ruano Pascual. Their best results to date are runner-up showings at Eastbourne and Wimbledon. Barely trailing them for Doha's last spot is Spanish duo Nuria Llagostera Vives and María José Martínez Sánchez, who have three Tour titles this year at Bogotá, Acapulco and Barcelona. Kveta Peschke and Lisa Raymond, who have been finalists at Paris [Indoors], Miami, Ponte Vedra Beach and Madrid, are in sixth place and don't have a huge deficit to make up either.

Asians Peng Shuai and Hsieh Su-Wei, who have won Sydney and Rome and were semifinalists at Roland Garros, are in seventh place, and Australian Open finalists Daniela Hantuchova and Ai Sugiyama are in eighth. Rounding out the Top 10 are Bethanie Mattek-Sands and Nadia Petrova and Roland Garros finalists Elena Vesnina and Victoria Azarenka.

The Sony Ericsson Championships - Doha 2009 - will be held October 27 to November 1.