Two-time defending champion Roger Federer needed a decider win to wreck the bottom-seeded David Nalbandian of Argentina in Shanghai on Sunday, as the top seed and world number one opened his campaign with a thrilling full-set victory at the ATP Tennis Masters Cup.

On the doubles' part, however, top-seeded twin pair from the United States, Bob and Mike Bryan, suffered a first match blow against seventh seeds Wayne Arthurs and Paul Hanley from Australia,beaten 7-5, 6-7(3), 7-6(4) in over two hours.

In the other men's doubles play late in the evening, fifth seeds Leander Paes of India and Nedad Zimonjic of Serbia and Montenegroover came fourth-seeded duo Mark Knowles from Bahamas and Daniel Nestor from Canada 7-5, 5-7, 6-3.

Joining Federer in victory in singles was the sensation of the late-season, Ivan Ljubicic, who send a second Argentine to defeat with his 6-2, 6-3 decision over Guillermo Coria.

Making his Masters Cup debut here with winning 20 of his last 23 matches, Ljubicic of Croatia cracked 6 aces and 25 winners against 21 unforced errors, and broke Coria for four times throughout thematch to win it in one hour and 18 minutes.

Federer 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.

"I'm very pleased the way I played, to have come through the match. I had no expectations whatsoever, to be honest," said Federer at a post-match news conference.

"For me, this is one of the better moments in my career because coming back from the worst injury I've ever had, to come back andwin a match at the Masters Cup. It's great for me," added the Swiss, who has missed six weeks of the season after spraining his right ankle in practice for Basel and was playing for the first time since winning the title at Bangkok on October 2.

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 then gave no chance to Nalbandian before breaking again in the seventh game and further holding his own serves for match victory.

"I was mentally ready for a two-sets defeat. I'm always sort of ready for that," said Federer. "Like I haven't been in this situation (down in the third set of a match) very often the last couple of years, obviously it's always difficult to come out of it.

"I really hoped that he would give me one opportunity, he did,and I took it. That was a great relief because I was getting a little bit not frustrated, but disappointed, playing such a good opening set and then having all my chances in the second set, then in the end suddenly finding myself 3-1 down in the third.

"I was just getting a little bit worried. But now that's in the past, so it's great," he said with a smile.

The top-ranked netman finally gave satisfactory to the match,especially when considering his status after long time sidelined due to injury, said: "I haven't played for seven weeks, so I know that I maybe keep missing too many returns. Occasionally I miss a shot or two more than maybe I usually do, but that's for me not really a concern...To start with a win in my group, that's definitely a cushion great to have.

Talking about his sustained right ankle, Federer said: "it's more mentally than physically. I could get to all the balls I wanted to, and to some I didn't because they were unplayable. Like I expected, maybe even better because a couple weeks ago I was on crutches and now I'm playing against the best in the world."

With the opening win, Federer extended his match-winning streak to 32, and improved his head-to-head record against Nalbandian though yet trailing 5-4.

The 24-year-old is attempting to become 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-endingglory, Federer has been drawn alongside another Argentine Guillermo Coria and Croatia's Ivan Ljubicic.

Nalbandian felt sorry about his third set where he wasted many chances before losing the match.

"I think I get my chance on there," said the Argentine. "I feel a little tired. In the third one, I couldn't serve pretty good. I missed a lot of first serve in that game (the 5th game in the decider). He broke me. After that, he played really good."

Though having played well from the middle of the second set onwards, Nalbandian wanted a win than just better performance,saying that "much better is to win. I know it's very important to feel good, to win one set. In the end of the week, it's will bevery important set, games and everything. But always better to win."

"I think I played very good in the second set, and then third set I start better than him. But the things can change any moment.So you always have to be careful. I couldn't take the chance.That's it," added Nalbandian.

Next on Tuesday, Federer will take Sunday's winner of the other Red encounter, Croatia's Ivan Ljubicic, while Nalbandian faces fourth seed Guillermo Coria.