Federer has been packing in his commercial responsibilities in the days leading up to the eight-man year-end showdown, which he has won for three of the last four years.
The 26-year-old put on a shaving demonstration for a crowd up around 1,000 raptured college men, who got to see the tennis hero up close.
Federer even demonstrated the shaving art using his sponsor's high-tech razor, then took questions submitted by the fans.
The winner of a dozen Grand Slams confirmed again that he hopes to play for another nine years and get as far as the 2012 Olympic event to be played a this beloved Wimbledon.
"I hope I play for a very long time," he said. "I'm healthy and fit."
Federer, who arrived in Shanghai on Monday, will not start his Red group play until the day after Sunday's start, when number two rival Rafael Nadal begins round-robin proceedings against Richard Gasquet.
Keeping his trademark humour and poise, the Swiss demonstrated a correct shave using a larger-than-life replica of his sponsor's newest product and a projection screen, then invited the crowd to do the same, with mirrors provided.