Novak Djokovic wins opening match in ATP World Tour Finals . The Serb will face Roger Federer on Sunday at the O2 Arena for a place in Sunday's final. Stanislas Wawrinka thrashes Tomas Berdcyh by same margin . First day wins for Roger Federer and Kei Nishikori .
Novak Djokovic wins opening match in ATP World Tour Finals . Beats U.S. Open champion Marin Cilic 6-1 6-1 . Stanislas Wawrinka thrashes Tomas Berdcyh by same margin . First day wins for Roger Federer and Kei Nishikori .