Serena Williams needed only 59 minutes to rout her Russian rival, improving to 20-2 all-time against Sharapova with her 19th consecutive victory in the rivalry.
Serena Williams is looking to match the all-time record of 24 Grand Slam singles titles won by Margaret Court when the year's final major championship gets under way Monday.
Maria Sharapova had earlier pulled out of the French Open 2019 with a shoulder injury
Maria Sharapova, a five-time Grand Slam champion, has not played since pulling out of a tournament in her native Russia at the end of January.
Umpire Alison Hughes was lucky to escape injury as the spider-cam ripped the sun shield right off her chair.
Australian Open 2019: Ashleigh Barty stunned five-time Grand Slam winner Maria Sharapova in a three-set thriller.
Maria Sharapova won 6-4, 4-6, 6-3 with the roof closed on Rod Laver Arena.
The pressure on the reigning French Open champion will only increase in her next round.
The Russian five-time Grand Slam champion was forced to stay up late in her second-round match.
The 31-year-old has only conceded three games en route to round three at Melbourne Park, where she won the title in 2008.
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.
Serena Williams won her 23rd title and seventh at Melbourne Park while eight weeks pregnant two years ago.
Simona Halep takes the top seeding among the women courtesy of her world number one ranking.
Maria Sharapova, ranked world number 29, decided to throw in the towel in the second set.
Wang Xinyu had to retire hurt, apparently after feeling pain in her thigh, while she was leading 5-2 in the second set.
The match between Maria Sharapova and Timea Bacsinszky lasted an hour 42 minutes.
Maria Sharapova laughed off suggestions that losing in the US Open fourth round represented the toughest period of her life.
Maria Sharapova was knocked out of the US Open in the fourth round on Monday, losing 6-4, 6-3 to Spanish birthday girl Carla Suarez Navarro.