World number one Serena Williams of the United States has made into the semifinals of the women's singles event of the US $4.5 million Sony Ericsson WTA Championships in Doha.

The top seeded Serena defeated Russian Elena Dementieva in straight sets 6-2, 6-4 in the quarterfinal to become first player to reach into the last four of the tournament.

Speaking to the media, Serena said that Dementieva is really a good and fittest player in the tournament, and her game will definitely become better and better in the upcoming years.

In another match, Serena's sister Venus William survived from scare of Russian Svetlana Kuznetsova 6-2, 6-7 6-4 to keep her hopes alive for reaching into the semifinals.

The 19-year old Caroline Wozniacki of Denmark beat Russian Vera Zvonareva 6-0, 6-7 and 6-4 in a White Group match even after struggling with unbearable cramps in her left thigh. The fourth seeded Wozniacki has not still lost any match in the tournament.