Zvonareva pushes Wozniacki for No 1

(AFP/Getty Images)

Just weeks after becoming the world's top-ranked women's player, Caroline Wozniacki will have to fight to keep that position at this week's WTA Championships in Doha.

The 20-year-old Dane will not face a challenge from the injured Serena Williams, whom she replaced as No 1, or Williams' sister Venus, who is also hurt. But Wozniacki will have to fend off Vera Zvonareva of Russia, the world No 2, whom she beat in a tough three-set match earlier this month at the China Open.

The eight-player tournament starts today with a round-robin group stage, with the top two players from each group advancing to the semi-finals.

Wozniacki and Zvonareva are in different groups but could face each other in the knockout rounds.