The German rose to world number one during a 2016 that yielded success in Melbourne and at the US Open, but she plummeted down the rankings after failing to match those standards last season.
It was the most anticipated match of the tournament so far but Kerber carried on the tremendous form she has shown to start the season and romped to a 6-1 6-3 victory in just 64 minutes.
Sharapova was put under more pressure by the two-time Grand Slam victor on her next service game but showed her fighting qualities to hold and keep herself in touch in the opener.
"I think she plays extremely well when she has a lot of matches behind her back", said Sharapova of Kerber.
I was really happy we have 2018 and not 2017.
Angelique Kerber at Australian Open
"I knew coming into the match that he was a great fighter, he grinds it out and gets a lot of balls back". "Anybody who knows me knows I never give up". I was really trying to play my game.
Prior to this encounter the Russian spoke of it being a good test for where she is, so a cursory 6-1 6-3 defeat does not tell an uplifting story.
Sharapova is playing here for the first time since serving a 15-month doping ban for testing positive for meldonium at the 2016 Australian Open.
Tomas Berdych ended 2009 U.S. Open champion Juan Martin del Potro's return to Melbourne Park for the first time since 2014 with a 6-3, 6-3, 6-2 win.
Her biggest problem here was Davis, ranked 76 but playing significantly above that, as she came from a break down to take the opening set in her first ever match against a world number one.
For both Kerber and Sharapova, quite a bit has changed since the Australian Open two years ago.More news: Trump campaign releases ad tying Democrats to murders by illegal immigrants
The Kerber-Sharapova match, billed as the showdown of the round, was over quickly.
"That's something I've been working on, and definitely improved in the match today".
Djokovic was equally convincing in his 6-2, 6-3, 6-3 rout of Spanish 21st seed Albert Ramos-Vinolas, although there was concern when he sought a medical timeout for treatment to his lower back.
Sharapova, who last made a Grand Slam final in 2015 here in Melbourne, admitted that in her time away during the suspension, it was tough to maintain her competitive balance because of the lack of actual matches.
Maria Sharapova has advanced to the third round, beating Anastasija Sevastova 6-1, 7-6 (4) as the temperatures began to rise at Melbourne Park.
'I have some figuring out to do, what happens to me in deciding moments in Grand Slams, ' he said after going down 5-7, 7-6 (7/3), 2-6, 6-3, 6-0.More news: Environment Canada predicts freezing rain for York Region Monday
"Of course this was quite a big match", Kerber, who began working with new coach, Wim Fissette, at the end of previous year, told reporters.
"I was struggling with everything, not the knee especially, the knee was still handling well", said Wawrinka, a three-time Grand Slam victor.
The third set was a non-event but Monfils burst back into life in the fourth and despite breaking for a 5-3 lead it was Djokovic who became flustered as he struggled to seal victory.
The 20-year-old Zverev has five titles on the elite tour but his fourth-round exit at Wimbledon last year remains his best run at a major.More news: Amazon Go tests retail waters with cashier-less convenience store