Serena Williams has been crowned as the new World number one women's tennis player . The 31 year old American beat Czech Republic's Petra Kvitova 6-3,3-6,7-5 to reach the Semifinals of Qatar Open Tennis Championship in Doha on her way to regain the number one spot after a gap of two and a half years. Serena takes on the defending champion Maria Sharapova in the Semifinals today. Sharapova cruised into the Semi finals defeating Samantha Stosur 6-2,6-4. In the other Semifinal, World Number two Victoria Azarenka plays the 4th seed Agniezska Radawanska . Azarenka beat Sarra Errani 6-2,6-2 on her way to the last four while Radawanska defeated Caroline Wozniacki 6-2,7-5.