Shanghai - Roger Federer went through what has become his annual sponsor obligation as he taught a group of Chinese teenagers how to shave at a public relations event as the countdown continued on Friday to the Masters Cup.

The Swiss top seed - number one Rafael Nadal is missing with right knee tendinitis - will open his title defence on Monday against France's Gilles Simon.

Federer showed quick hands off the court as he brandished a microphone in one fist and a razor in the other during the "first shave" with a group of local 18-year-olds.

Round robin play starts on Sunday at the Qi Zhong stadium as Novak Djokovic faces Argentine Juan Del Potro followed by Nikolay Davydenko against Jo-Wilfried Tsonga, last weekend's Paris winner.

Federer, who quit in Paris a week ago as a precaution due to back pain, has spent the last few days in rainy and foggy Shanghai getting re-accustomed to conditions at the venue where he has lifted the last two titles.

And unlike Nadal, who has run out of energy and fallen victim to injury after claiming eight trophies this season, the 27-year-old Federer seems again to be primed for the year-ender.

"All eight guys (in the field) have a chance to show what they got," he said in the run-up. "I've been very successful at the last event of the season.

"I always seem to have something in the tank and indoors on hardcourt is one of my favourite surfaces."

Federer, a 13-time Grand Slam champion, is aiming to join Pete Sampras and Ivan Lendl as the only players to win five year-end titles.

The Swiss is well on track with a 26-3 record in season-ending play, winning four of the last five Masters Cups played in Houston and Shanghai.

He lost the 2005 final in the first year of Shanghai to David Nalbandian.

"I hope I can repeat some of the great efforts that I've had here," he said. "This is the last time it will take place in Shanghai.

"It's been a good year for me and I hope to finish well."

Federer heads the Red group with US Open finalist Andy Murray, American Andy Roddick and France's Simon while Djokovic, Davydenko, and newcomers Tsonga and Del Porto make up the Gold group.

While Federer leads the field in China, Nadal is stuck at home on the island of Mallorca resting his knee, taking treatment and hoping for a miracle with the Davis Cup final against Argentina set in a few weeks.

The world number one, who has never claimed the ATP year-end title, is desperate not to miss the Davis date at Mar del Plata against Argentina.