Maria Sharapova's dream of ending the season as the world number one is over. She has pulled out of the WTA Championship with an injury after losing her second match to Li Na, meaning Caroline Wozniacki remains the world's top player.

Sharapova withdrew from the tournament without a win after her surprise opening defeat to Samantha Stosur.

On Wednesday evening, the Russian conceded the first set to Li Na on a tie break, and then lost the second set 6-4.

This was the first win for the French Open champion since August.

Li Na is now second in the White Group behind Belarus’s Victoria Azarenka who won her opening group match against Sam Stosur. It was a comfortable straight sets victory for the fourth seed, who took control from the baseline, automatically made her the group’s favorite.

Meanwhile, despite Caroline Wozniacki holding onto her world number one status, she might not make the semis in Istanbul.

She lost to Vera Zvonareva in three sets, 6-2, 4-6, 6-3. The Russian is now second in the group behind Wimbledon champion Petra Kvitova with a match left to play. Only the top two progress to the last four of the competition.