Rafael Nadal is bidding to become the first man in the Open era, and only third in history along with Roy Emerson and Rod Laver, to win each Grand Slam on two or more occasions.
The Spanish second seed is bidding to become the first man in the Open era, and only third in history along with Roy Emerson and Rod Laver, to win each Grand Slam on two or more occasions.
Fifth seed Kevin Anderson also progressed against Adrian Mannarino, with last year's Wimbledon finalist through 6-3, 5-7, 6-2, 6-1.
Sharapova, a winner at Melbourne Park in 2008 who has failed to impress at Grand Slam level since returning from a doping ban in 2017, signalled her intent with a 6-0, 6-0 thrashing of Britain's Harriet Dart, who ended the match in tears.
Playing in her 15th Australian Open, the three-time finalist said she was pleased to go through so easily as she battles back from injuries.
"I'm still working through some painful days. But, you know, I felt like I did all the right things today in order to get through that match."
Fifth seeded Sloane Stephens, the 2017 US Open champion who struggled in her warm-up tournaments in Brisbane and Sydney, got back to business against fellow American Taylor Townsend in a 6-4, 6-2 win.
Eleventh seed Aryna Sabalenka from Belarus also safely negotiated round one on a day when temperatures were soaring towards a forecast 37 Celsius (98.6 Fahrenheit).
But Germany's 14th seed Julia Goerges, who won the recent Auckland Classic, crashed out in three sets to American Danielle Collins.
Britain's Katie Boulter, meanwhile, created a slice of history by becoming the first woman to win in a third set tiebreak -– a new rule introduced to the Open this year.
Instead of playing to the death, third or fifth sets now go to a tie-break when the score reaches 6-6 and it becomes the first to 10.
It seemed Boulter wasn't told, fist-pumping and walking to the net at 7/4 before being reminded of the new rule. She went on to beat Russia's Ekaterina Makarova 6-0, 4-6, 7-6 (10/6).
Swiss maestro Federer, seeded three, has won the last two Australian Opens and is gunning for a record seventh crown and 21st Grand Slam title.
Scottish former world number one Murray tearfully revealed last week that severe pain from a hip injury was proving too much to bear and he planned to retire this year.
He would like to finish at Wimbledon, but admitted the Australian Open could be his last tournament.
Spain's 22nd seed Roberto Bautista Agut is the man who could draw the curtain on Murray's time in Melbourne, where he has been a five-time finalist.
Denmark's Wozniacki broke through for her first Slam title in Melbourne last year, beating Simona Halep in the final, and gets her tournament underway against Belgium's Alison van Uytvanck.