( CNN ) -- Caroline Wozniacki beat Ana Ivanovic in a battle of former world number one ranked players to reach the semifinals of the $ 2 million WTA tournament in Dubai Thursday . The Dane , who lost the top spot during the Australian Open earlier this year , won an entertaining encounter 6-3 7-5 in one hour 33 minutes . Former French Open champion Ivanovic threatened a comeback when she twice retrieved deficits in a thrilling second set , but Wozniacki achieved her sixth break of service to lead 6-5 and serve for the match . Ivanovic saved one match point but hit a return long on the second to leave defending champion Wozniacki on course to defend her title . Her semifinal will be against Julia Goerges , the improving German , who beat Slovakian star Daniela Hantuchova 4-6 6-3 6-4 in their last eight match . The unseeded Goerges has beaten Wozniacki the last two times they have met , both on clay . Wozniacki is the highest ranked player left in the tournament after the withdrawals of Victoria Azarenka and Petra Kvitova through injury . Earlier , Agnieszka Radwanska of Poland reached her second semifinal in two weeks by thrashing German Sabine Lisicki 6-2 6-1 . The fifth seed will play in-form Jelena Jankovic in their last four clash Friday . Jankovic , also a former world number one , upset fourth seed and reigning U.S. Open champion Samantha Stosur 6-4 6-2 to reach her fifth Dubai semifinal since 2005 .
Caroline Wozniacki beats Ana Ivanovic 6-3 7-5 in Sabine Lisicki Open quarterfinals . Both players have been former world number 6-3 ranked . Agnieszka Radwanska thrashes Dubai in their quarterfinal . Sam Stosur beats Caroline Wozniacki to reach the semifinals .