Meanwhile, in the day's other match, tournament favourites Ivory Coast were held to a 0-0 draw by a stubborn Burkina Faso in their opening Group B match at the Estadio do Cabinda.
Federer had already qualified as Group B winner before beating Mardy Fish 6-1 3-6 6-3 in Thursday's opening match, handing the eighth-ranked American a third successive defeat in his debut at the tournament.