Top-ranked Aryna Sabalenka is favourite to win a third Australian Open in four years but faces strong competition from a United States contingent led by Coco Gauff and defending champion Madison Keys.
World No 2 Iga Swiatek is another big threat while two-time Melbourne champion Naomi Osaka will hope to be in the mix when the first Grand Slam of the year begins on Sunday.
Keys stunned title-holder Sabalenka 12 months ago in a classic three-set final to win her first major title aged 29.
But she failed to kick on from there, not winning another tournament all year, and the world No 9 will have a target on her back as the title holder.
Three other Americans are ranked inside the world's top 10: Gauff (third), Amanda Anisimova (fourth) and Jessica Pegula (sixth).
The 21-year-old Gauff last year beat Sabalenka at the French Open for her second major crown, but her best performance on the Melbourne Park hardcourts was making the semifinals in 2024.
Speaking at the mixed-teams United Cup, where she launched her 2026 campaign, Gauff said she spent the off-season "just overall becoming better and more comfortable with my game".
Her serve has been her biggest failing and she suffered a surprise defeat to Spain's Jessica Bouzas Maneiro at the United Cup, but recovered to defeat Swiatek 6-4, 6-2 in a statement victory.
It was Gauff's fourth win in a row over Swiatek.
The 24-year-old Anisimova has emerged as a serious threat after enjoying the best year of her career in 2025, reaching the finals of Wimbledon and the US Open, and winning 1000 titles in Beijing and Qatar.
She also made the season-ending WTA Finals for the first time, going down to Sabalenka in three sets in a high-octane semifinal.
"She always pushes me to play my best tennis," said Sabalenka.
Like Pegula, a first major title remains elusive for Anisimova despite going close.
Swiatek, Sabalenka's long-term rival for the top ranking, is overdue something special in Melbourne.
The Pole is a six-time Grand Slam champion and the Australian Open is the only major she has yet to win.
She matched her best Melbourne performance by reaching last year's semifinals, and did so in rampant style, only to lose to an inspired Keys.
"At a Grand Slam you have to really play great for two weeks, not have any bad days, be consistent," the 24-year-old said at the United Cup.
Japan's former world No 1 Osaka would be a popular winner if she were to add to her 2019 and 2021 Melbourne triumphs.
Now ranked 16th, the 28-year-old must rank as an outsider, capable of conjuring up her best tennis in flashes but unable to do it consistently and stay fit for long stretches.
World No 5 Elena Rybakina, the Moscow-born Kazakh, is another to watch.
IMPERIOUS SABALENKA
It is hard to look beyond Sabalenka.
Having been stunned by the unfancied Keys, the Belarusian suffered more Grand Slam heartbreak in the French Open final against Gauff.
She then went down to Anisimova in the Wimbledon last four, before roaring back to get revenge over the American and retain her US Open title.
The Australian Open champion in 2023 and 2024, Sabalenka will be in an unfamiliar role when she goes into the tournament as runner-up from 12 months ago.
"Honestly, there is no difference," the hard-hitting Sabalenka said in Brisbane this month, where she won the title for a second successive year in an ominous statement of intent.
"Every time, if I'm defending champion, if I lost first round last year, the goal is always the same – to bring my best tennis and to improve my game."
Outside the title contenders there will be fascination in how Venus Williams performs when she becomes the oldest woman to play in the main draw at Melbourne.
The seven-time Grand Slam singles champion was handed a wildcard aged 45.
The American, who has played only a limited number of singles matches in recent years, will compete at the Australian Open for the first time since 2021.