World number one Roger Federer made a winning return from injury on Monday, opening the defence of his Masters Cup crown with a ruthless 6-1, 7-6 win over Gaston Gaudio.

A left thigh strain suffered while preparing for his home tournament in Basel nearly a month ago had threatened to cut Federer's season short.

But the 23-year-old Swiss was quickly back at his brilliant best, easing past the French Open champion in 91 minutes and with a minimum of fuss.

Having not played competitively since claiming his 10th title of the season in Bangkok six weeks ago, Federer could not have asked for a better opponent for his opening round-robin match of the $4.45-million season finale.

The only debutant in the elite eight-player field, Gaudio's prowess on clay is in sharp contrast to his struggles on the North American hardcourts having claimed just two wins on the surface since the U.S. Open.

Between them Federer and Gaudio captured all the Grand Slam titles on offer this season, the Swiss taking Wimbledon, Australian and U.S. Open while the Argentine took the French Open to prevent a sweep.

But Federer's all-court game was simply too much for the Argentine baseliner.

"I'm quite relieved to have played my first match and come back after a long time without a tournament, without playing a match," said Federer, after posting his 19th consecutive win over a top-10 ranked opponent.

"I'm very happy with my game. I went two weeks without playing. It is something I've never done before except maybe the end of a season.

"Beating a player like Gaston is very satisfying.

"I had my chances and was playing well, hitting a lot of winners. In the second set I made some errors and that made it even.

"I'm not worried I could push 100 per cent no problem."

Under heavy, grey skies the match got off to a stuttering start, Federer taking the opening game before rain hit the Westside Tennis Club delaying play for two hours and 20 minutes.

When play resumed, Gaudio held serve but Federer seized control on his next opportunity hammering a running forehand winner down the line to break the Argentine and go up 3-1.

Now back to his familiar flowing rhythm, Federer stormed through the next four games taking the set in just 31 minutes.

In the second, Gaudio offered some stern resistance but the feisty Argentine was never able to penetrate Federer's defences failing to gain a break point the entire match.

If Federer's game was lacking anything it was a bit of his killer instinct, converting just two of 21 break opportunities before finally clinching the second set and match 7-4 in the tiebreak.