Defending champion Roger Federer needed a decider win to wreck the bottom-seeded David Nalbandian of Argentina as the world number one opened his campaign with a thrilling full-set victory at the ATP Tennis Masters Cup.

The 24-year-old made a successful first serve to improve 2 match points in hand into a final win of 6-3, 2-6, 6-3 in 1 hour and 55 minutes.

Trailing two games to one in the decider, Federer was broken at as early as the fourth game when the superlative Swiss being forced to defend his play on the baseline under the pressure from the 23-year-old Nalbandian, the last man to qualify for this year's season-ender.

Making a sudden but strong comeback in the following, Federer broke back after winning a over-ten hits rally and moving his 12-ranked opponent around the court with placement shots in the fifth game.

The Swiss, playing for the first time since winning the title at Bangkok on October 2 and having missed six weeks of the season after spraining his right ankle in practice for Basel, then gave no chance to Nalbandian before breaking again in the seventh game and further holding his own serves for match victory.

Federer is attempting to beome the first man to win the Tennis Masters Cup three times, and the first man to win a year-end championships three times since pete Sampras, who won the last of five ATP Tour World Championships titles in 1999.

Lone in the Red Group as a hot favorite for the year-ending glory, Federer has been drawn alongside another Argentine Guillermo Coria and Croatia's Ivan Ljubicic.

Playing first Master Cup with a special competition system with round-robin, the top two finishers in each group qualify for the semi-finals of the 4.45 million US dollars tournament, featuring the top eight players for the season.