World number one Roger Federer and fourth-seeded Ivan Ljubicic both notched up impressive wins at the Masters Cup in Shanghai while Argentine Nalbandian's prospects of advancing into the semifinals and further defending his title became gloomy.

25-year-old Federer, presented with the ATP 2006 Race trophy for his number one ranking on Monday, showed his skill to beat Roddick 4-6, 7-6 (8), 6-4 in two hours and 29 minutes.

In the other Red Group match, Croatian Ljubicic struggled into Wednesday morning to seize his first round robin win by over-powering Nalbandian with 30 aces 5-7, 7-6 (7), 7-5.

The 30 aces were the most in a tennis Masters Cup match since 1996 when countryman Goran Ivanisevic fired 35 aces in his 6-7, 7-6, 7-5 loss to Pete Sampras in the ATP World Championships semifinals.

"I was really happy to be here to compete in the Masters Cup after being sidelined for about three weeks due to injury. It was fantastic to win this horrible match. It is emotional, I'm just keeping fighting and fighting," said Ljubicic, who made his second appearance at the yearend finale.

"And I feel physically good from the first point to last point. If I can play the way I did today, I will have a chance to beat Federer."

He lost his first match to American Andy Roddick on Sunday and will play Federer on Thursday.

In men's doubles, the Bryans from America beat Martin Damm of Czech Republic and Leander Paes from India 6-2, 6-7 (4), 7-6 (5) in their second round-robin match to keep their hopes alive.

The world number one twin brothers lost their opening match to Israelis Jonathan Erlich and Andy Ram.

In an earlier doubles match, the Israeli pair, seeded seventh, surrendered to Australia's Paul Hanley and Zimbabwe's Kevin Ullyett 6-4, 6-4.

In the day's most absorbing match, Federer beat Roddick yet again to move to 12-1 against the American.

"It's just frustrating, you know, I was real close tonight. I think that makes it a little bit harder, knowing you are one of your best victories, just shots away, one serve away," said a heartbreak Roddick, who lost to Federer at 6-2, 4-6, 7-5, 6-1 in the US Open final in September.

"But at the same time I remember where I was four or five months ago as far as my career. It definitely feels like it's on the upswing tonight. I felt like I was unlucky not to win that one tonight. I was the better player for two sets tonight."

Federer, who came into Shanghai with an ATP-best 11 titles in a career-high 15 finals and extended his unbeaten run to 26, voiced the same ideas as his opponent.

"Tough loss for him but for me it was a bit of relief, of course, it was really a close match. I just got a bit luck at the end. At that moment I guess if I could have lost one match, it would probably have been this one," said Federer, who scored 109 points out of a total 215, just three more than the fast -improving Roddick.

"I think he played the perfect match for two sets. Maybe one serve lacked in the end, you know, so it was unfortunate for him."

As it stands, Federer has two victories in hand while Ljubicic and Roddick are tied on one win and one loss in Red Group. Conceding two defeats, defending champion Nalbandian still has a slim chance to make it to the semifinals.

(Xinhua News Agency November 15, 2006)