Rafael Nadal survived a stern examination of his title credentials to edge out the brilliant Mardy Fish in a late-night classic at the ATP World Tour Finals, BBC reported. Nadal had not played a competitive match since 13 October and it was all-too apparent as eighth seed Fish fought back from losing the first set to threaten a massive upset.The crowd at London\'s O2 Arena were treated to a titanic decider as the clock ticked and both men gave absolutely everything to secure an opening-day win.Nadal eventually emerged triumphant at 2329 GMT, winning 6-2 3-6 7-6 (7-3) in two hours and 53 minutes of enthralling competition.The event organisers could not have wished for a better start to the season-ending championship - with Roger Federer\'s victory over Jo-Wilfried Tsonga also going the distance earlier on Sunday.