Melbourne - Will Serena Williams make a triumphant return to the scene of her last Grand Slam win, can Caroline Wozniacki defend her crown or is Naomi Osaka capable of back-to-back majors?
AFP Sport picks five women to watch when the Australian Open begins in Melbourne on Monday:
1. Caroline Wozniacki
The Dane finally broke her Grand Slam hoodoo in Melbourne 12 months ago after 12 years of trying, and is determined to prove she remains a force at the top level after dropping the bombshell that she is suffering from rheumatoid arthritis.
Wozniacki, 28, says the debilitating auto-immune condition is so bad that on some days
"I wake up and can't lift my hands over my head". The shock diagnosis came after Wozniacki had returned to number one and taken her WTA tour title tally to 30 with victories not only in Melbourne, but also Eastbourne and Beijing.
She arrives ranked three believing she can control her condition.
"I've been feeling well. I've learned to cope after matches."
2. Simona Halep
The Romanian bounced back from losing to Wozniacki in an epic Melbourne final 12 months ago to claim her own maiden Slam at Roland Garros and climb back to number one despite a nagging back injury that forced the 27-year-old to miss the WTA Finals in Singapore.
Top-seeded Halep is without a coach after long-time Australian mentor Darren Cahill stepped down for family reasons, and described 2018 as "very emotional" but insisted it had made her mentally stronger.
"When you have a target on your back it's not easy because everyone wants to play their best against you and beat you," she said. "But being number one is something you should embrace and be proud of."
3. Angelique Kerber
The Wimbledon champion and world number two will turn 31 on January 18 and is tipped to unveil a more aggressive approach under new coach Rainer Schuttler, who reached the Australian Open final in 2003 where he lost to Andre Agassi.
Schuttler will add more "daring" to the 2016 Australian Open champion's game, said the German Tennis Association's Barbara Rittner, who helped develop Kerber as a teenager.
"In general, it's about her offensive game," Rittner told Deutsche Welle of the three-time Grand Slam champion who lost an agonising, breathless semi-final 9-7 in the final set to Halep in Melbourne last year.
"She is unbelievably good with the volley - in this more aggressive, more daring game. I'm sure they'll work on it."
4. Naomi Osaka
The popular 21-year-old's US Open triumph was overshadowed by Serena Williams' tantrum in the final at Flushing Meadows but Osaka has the opportunity in Melbourne to demonstrate she can withstand the spotlight of being the new standard bearer for tennis in Japan, Asia and the next generation of women.
She arrives as second favourite with the bookies behind Williams, and seems unfazed both by her stratospheric rise and by the prospect of the huge support she could receive at the Australian Open, often dubbed the Asia-Pacific Grand Slam.
"I never feel pressure to perform. I enjoy Grand Slams the most," she said. "There is a certain degree of pressure, but it's from myself."
5. Serena Williams
Despite being ranked outside the top 10, few would be brave enough to count Williams out of the equation as she aims to equal Margaret Court's all-time record of 24 Grand Slam singles titles. The 37-year-old has won at Melbourne Park seven times, most recently on her last visit in 2017 when she was eight weeks pregnant with daughter Alexis Olympia.
She has already been installed as a short-priced favourite, with the odds-makers confident she won't repeat her infamous US Open final meltdown where she called umpire Carlos Ramos "a thief" and was given three code violations to lose a game and derail her challenge. Williams missed the chance to equal the record in both the Wimbledon and US Open finals last season and says she is now avoiding focusing on the numbers.
"It truly makes me excited for what's ahead in 2019," she said. "I always have crazy big goals but I like to keep them to myself. I think keeping them a bit of a secret helps me do the best I can."