Germany’s Angelique Kerber and Argentina’s Juan Martin Del Potro have clinched spots in the year-end Championships of their respective Tours.

By reaching the Linz semifinals, Kerber earned the eighth and final singles place in the WTA Championships, to be held at the Sinan Erdem Dome in Istanbul, Turkey, from October 22-27.  Other qualifiers are Serena Williams, Victoria Azarenka, Agnieszka Radwanska, Li Na, Petra Kvitova, Sara Errani, and Jelena Jankovic. No. 3 Maria Sharapova withdrew with a shoulder injury; there will be no Russian woman in the singles field for the first time since 1997.

Del Potro secured a berth in the Barclays ATP World Tour Finals with his upset of No.1 Rafael Nadal in the semifinals of the Shanghai Masters.  He joins Nadal, Novak Djokovic and David Ferrer in qualifying for the year-end tournament at the O2 arena in London, November 4-11. With No. 3 Andy Murray sidelined post back surgery, there are still four spots up for grabs in the eight-man field.