Caroline Wozniacki enters a Grand Slam as the defending champion for the first time. She has played first-round opponent Alison Van Uytvanck only once before, winning, 6-1, 6-4 on the clay courts of Rome.
Victoria Azarenka was the last player to successfully defend the Australian Open title back in 2013.
Naomi Osaka is seeking to become the first female winner of back-to-back majors since Serena Williams picked up the French Open and Wimbledon in 2015 to complete her second 'Serena Slam'. Magda Linette is up first for the Japanese, who lost the only previous meeting between the pair in Washington last year.
WTA World No.2 Angelique Kerber is the highest-ranked player in action on day one. She faces Polona Hercog, who she is tied 2-2 in the head-to-head record against. The pair have never gone to three sets, while Kerber won their previous Grand Slam match-up at the US Open as the Slovenian retired at the start of the second set.
Kerber is one of 11 players who could possibly overtake Simona Halep as WTA World No.1 at the end of the tournament.
Maria Sharapova, who will get things going on Rod Laver Arena, stands fourth all-time for main draw matches at the Australian Open with 67. Serena Williams leads the way with 91 – 24 more than Lindsay Davenport and sister Venus.
Croatian pair Donna Vekic and Petra Martic have been seeded at a Grand Slam event for the first time, at 29 and 31 respectively. No.21 seed Wang Qiang is the other player in this position.
Vekic has lost both of her previous encounters with first-round rival Kristina Mladenovic, but both of these were in 2014, when she was lower ranked than the Frenchwoman.
Julia Goerges (Auckland), Aryna Sabalenka (Shenzhen) and Petra Kvitova (Sydney) have all won tournaments so far this season.
ORDER OF PLAY
Sam Bruce of ESPN takes a look at the weight of expectation on Australia's home stars, including Ashleigh Barty, ahead of the 2019 tournament.
Why women's sport will miss Andy Murray, by Eurosport's Jen Offord.
Will the 2019 Australian Open start a dominant year for Serena Williams? Tennis.com's Steve Tignor explores the issue.