Clinical Djokovic sets up Nadal showdown at Tour Finals LONDON (Reuters) - Defending champion Novak Djokovic set up a title showdown against Rafa Nadal at the ATP World Tour Finals with a 6-3 6-3 defeat of Switzerland's Stanislas Wawrinka on Sunday. The Serb, who lost his number one ranking to Nadal in October, was too solid for Wawrinka in the day's second semi-final as he racked up a 14th consecutive victory over the 28-year-old. Djokovic used all his defensive skills in the eighth game of the first set to convert a break point for a 5-3 lead and took the opener with an ace. Wawrinka, who has made the semi-finals on his debut appearance at the season-ending showpiece, hung on grimly in the second set after dropping serve but Djokovic was clinical as he stretched his winning streak to 21 matches. In the first semi-final Nadal beat Wawrinka's fellow Swiss Roger Federer 7-5 6-3.