Djokovic relishes Federer duel

World number one Novak Djokovic will meet Switzerland's Roger Federer, his closest pursuer in the rankings, in the final of the World Tour Finals. The Serb, who is unbeaten in four matches at this year's ATP Tour finale, is in his first O2 Arena final since the event moved to London in 2009. He said: "Knowing it's the last match of the season, I'm really going to give my best physically and mentally." Djokovic, 25, will finish 2012 as world number one regardless ofhe result. He leapfrogged Federer in the standings after the Swiss decided not to play in the Paris Masters, sacrificing the ranking points he had secured by winning the event the previous year .