The Swiss tennis great Roger Federer gave a masterful display to begin his Australian Open title defence, losing just five games in his straight sets win over unseeded Slovakian Lukas Lacko.
The world number two, eyeing a 17th Grand Slam title, will play Frenchman Gilles Simon next.
Third seed Novak Djokovic was similarly untroubled as he disposed of Spain's Marcel Granollers.
Tomas Berdych and Andy Roddick won comfortably, but there were defeats for Sam Querrey and Nikolay Davydenko.
Women's top seed Caroline Wozniacki overcame a nervy performance to beat Argentina's Gisela Dulko in straight sets.
Fourth seed Venus Williams and 14th seed Maria Sharapova both had comfortable wins, while 2004 champion Justine Henin came from a set down to beat India's Sania Mirza in three.
