* Dementieva announces retirement from tennis
* Zvonareva defeats Clijsters in White Group (adds last game)
Elena Dementieva lost 6-4 6-2 to Italy's Francesca Schiavone at the WTA Championships on Friday before stunning the crowd by announcing her retirement from tennis.
In the White Group, Vera Zvonareva beat Kim Clijsters 6-4 7-5 while Victoria Azarenka beat Jelena Jankovic 6-4 6-1 to round out the group stage of competition.
The 29-year-old Dementieva, making her 10th appearance at the prestigious tournament, blinked away tears as she thanked her fans around the world and paid tribute to her mother Vera for her support throughout her career. [ID:nSGE69S0KX]
"I would like to thank all the people around the world for supporting me," the Russian told the crowd as her mother and fellow competitors wiped away tears at the Khalifa Tennis Complex in the Qatari capital.
"I'm so emotional and it's so hard to say goodbye."
Dementieva and Schiavone had already been eliminated from the Maroon Group after Caroline Wozniacki and Sam Stosur sealed semi-final spots a day earlier, but with year-end ranking points and $100,000 on offer for the win neither player lacked motivation.
French Open champion Schiavone, making her singles debut at the $4.55 million season-ending tournament, suffered an early break but hit back immediately and moved into a 4-2 lead.
Dementieva broke in the seventh and then levelled at 4-4 but the 30-year-old Schiavone regained the momentum and skipped with delight after sealing the set 6-4.
The Italian upped the tempo in the second set and quickly got the measure of Dementieva's serve and wrapped it up 6-2.
World number two Zvonareva maintained her perfect record in the White Group with an impressive straight sets victory over Belgian Clijsters.
The Russian, who moments before the match bade an emotional farewell to Dementieva, was the only player to go through the group stage unbeaten and will play Wozniacki in the semi-finals on Saturday. Clijsters will play Stosur for a place in the final.
Zvonareva said Wozniacki would present a tough challenge.
"Caroline is a great player. She's No. 1 in the world," the Russian added.
"I know if I play my best tennis I can beat anyone on the other side of the net. But I know it's not easy to produce your best tennis every day."
In the day's last match, Azarenka of Belarus proved too strong for Serb Jankovic, who was the only player to lose all three of her group games.