Defending champion Venus Williams and first-time qualifier Victoria Azarenka secured berths at the prestigious Sony Ericsson Championships in Doha, Qatar.
"Qualifying for the year-end tournament is always a goal I set for myself at the beginning of the season and I am excited to have an opportunity yet again to compete with the best players in the world," said the world No.3 Williams, who has qualified for the ninth time in her career.
The world No.9 Azarenka said: "Winning my first Tour title and reaching the Top 10 for the first time in my career has really made my year and I couldn’t think of a better place to finish it than in Doha. Having an opportunity to travel to the year-end Championships is an accomplishment I am very proud of."
As the top eight singles players of the season are competing at the season-ending Championships, and as five have already qualified (Dinara Safina, Serena Williams, Elena Dementieva, Caroline Wozniacki and Svetlana Kuznetsova), there is just one more berth left to fill.