Roger Federer of Switzerland serves to Gilles Simon of France during their Masters Cup tennis match in Shanghai yesterday. Federer lost to Simon 6-4, 4-6, 3-6.- Xinhua

Top seed Roger Federer played an uncharacteristic and erroneous game as he lost to Gilles Simon of France in his first match of the Tennis Masters Cup here on Monday.

The Swiss, who was made the first seed at the injury-forced absence of World No. 1 Rafael Nadal, made a spate of 50 unforced errors compared to Simon's 38 on his way to the 4-6, 6-4, 6-3 loss.

Like Simon, another Masters Cup debutant Andy Murray of Britain beat Andy Roddick of the United States 6-4, 1-6, 6-1 in another group match.

Federer, whose shots seemed not as sharp as before, blamed his loss on self-doubt about his back conditions and lack of practice.

"I was sort of skeptical going into the match because the practice sessions haven't been hard at all. I really tried to not push it at all. So I was actually happy that the back felt okay," he said.

"I had matches in Basel I was serving 15 aces. Here I was serving three aces. Definitely it was a factor today, you know, the serve. I haven't been basically serving all week, except maybe50 serves in total," he said.

"The shoulder gets a little rusty and things don't work out the way you want it. I still expect myself to have more serves in. I didn't serve full blast especially from the start. So I don't know if that cost me the match," he added.

Simon, who beat Federer in their only past encounter, reckoned that the serve had somewhat failed Federer.

"His serve was a little bit slower than usual. He has a good serve, but his serve is not that fast, so it was a little bit easier for me," he said.

Federer, the winner of 13 grand slam titles, was in crisis this season as he lost to Nadal in the finals of the French Open and Wimbledon, and relinquished the world number one spot to the gritty Spaniard.

He managed to arrest his downturn in the US Open where he beat Andy Murray to retain the title, and pledged to take the Masters Cup tournament as a launching pad for another period of supremacy.

He is still the man of the local fans who chanted his name and even sometimes applauded when the No. 8 seed Simon mishit a shot.

Federer gratified them by producing some scintillating performance in the fifth game of the first set to break Simon and led the score by 3-2.

He rounded off the first set with his belated but effective first ace in the match. He got off to promising start in the second set where he broke Simon's serve in the third game.

But his performance faltered in the ensued game and Simon broke back to level the score at 2-2. From then on, the former number one was apparently struggling before the combative Simon and was broken in the tenth game to award the Frenchman the win of the set.

Simon broke Federer's serve in the eighth game of the third set en route to his opening victory. Federer can take some comfort from his last year's experience here when he lost his opening match but ended up as the eventual winner of the prestigious tournament.

"It's great. It's the only tournament where I really have a chance after losing the first rounds," he said.

Federer will play his next group game tomorrow.