Serena Williams underlined why she is the Australian Open favourite with a rapid first-round win, while defending champion Naomi Osaka also advanced.
Williams, chasing a record-equalling 24th Grand Slam title, took the first set in 19 minutes in a 6-0 6-3 victory over Russia’s Anastasia Potapova.
Third seed Osaka started slowly against Marie Bouzkova before winning 6-2 6-4.
World number one Ashleigh Barty and Britain’s Johanna Konta are also in action on Monday.
Osaka, who broke the net with one of her serves against Czech Bouzkova, will play China’s Saisai Zheng in the second round in Melbourne.
Williams, who won her first WTA title in three years in the run-up to the opening Grand Slam of the year, will play Slovenia’s Tamara Zidansek or South Korean wildcard Han Na-lae next.
Other winners on day one were Croatian 13th seed Petra Martic, who beat American Christina McHale 6-3 6-0 to set up an encounter with 2018 Wimbledon semi-finalist Julia Goerges of Germany, and 14th seed Sofia Kenin.
But last year’s Wimbledon semi-finalist Barbora Strycova was beaten 6-2 7-6 (7-5) by Romania’s Sorana Cirstea.
The tournament went ahead as scheduled on Monday after air quality improved in Melbourne.
Last week’s qualifying event had been disrupted by delays because of the air pollution caused by widespread bushfires.