Gauff again took an early lead in the second set and this time made it count, wrapping up the contest in an hour and 37 minutes.

Heavy rain at Melbourne Park meant that play was restricted on the first day of the tournament, but Roger Federer, Noami Osaka and Serena Williams, who is chasing a 24th grand slam, were all in action on Rod Laver Arena.

All three emerged unscathed in straight sets -- defending champion Osaka defeating Czech Republic's Marie Bouzkova 6-2 6-4, Williams breezing past Russian Anastasia Potapova 6-0 6-3 and Federer bettering USA's Steve Johnson 6-3 6-2 6-2.

Caroline Wozniacki, who won her sole grand slam title in Melbourne two years ago and will retire after this year's tournament , also made light work of her first round match, defeating Kristie Ahn 6-1 6-3.

Competing in the main draw for the first time in Melbourne, Gauff raced into an early lead in the opening set but failed to capitalize on her advantage.

Williams, 24 years her opponent's senior and playing in her 85th major, pulled back at the end of the set before going down 7-5 in a tense tie break.