Roger Federer edges past Stanislas Wawrinka, sets up ATP World Tour final showdown with Novak Djokovic

Roger Federer saved four match points, before winning a gripping semi-final, in a deciding set tiebreak against fellow Swiss Stanislas Wawrinka on Saturday, to set up a dream ATP World Tour Final climax with Novak Djokovic.Six-times champion Federer survived a nerve-shredding battle before emerging victorious, 4-6 7-5 7-6(6), in the standout match of the week at London's O2 Arena, despite Wawrinka's fightback.Serving at 5-4 in the final set, Wawrinka lost his nerve and watched three gilt edged chances slip agonisingly by, the second of which was a feeble volley into the net that will give him nightmares.As the intense duel moved into the tiebreak, both men looked out on their feet. Wawrinka had another match point at 6-5, this time on Federer's serve, but again he could not take it.Federer then completed a remarkable two hour 48 minute victory in the coolest manner possible, producing a nerveless drop volley to end the contest.Earlier world number one Djokovic beat Japan's Kei Nishikori, in three sets in the other semifinal.