Novak Djokovic defeats Stan Wawrinka in straight sets . Stan Wawrinka can secure Thursday World No.1 spot with victory in final group match . `` I think today was more about fighting and getting through it , '' Berdych said . Marin Cilic overcomes Novak Djokovic in straight sets . Roger Federer faces Andy Murray on end of year .
Novak Djokovic defeats Stan Wawrinka in straight sets . Stan Wawrinka can secure Thursday World No.1 spot with victory in final group match . Marin Cilic overcomes Novak Djokovic in straight sets . Roger Federer faces Andy Murray on end of year .