MELBOURNE -- Iga Swiatek will be a hot favorite to win a first Australian Open when it begins on Sunday, but could face a stiff challenge from former champions Aryna Sabalenka and Naomi Osaka.

AFP Sport highlights five women to watch at first Grand Slam of the year:

Iga Swiatek

The world number one is a four-time Grand Slam champion but has never been beyond the semi-finals at Melbourne Park.

The Polish player rocketed back to the top of the rankings after winning her first WTA Finals trophy in November.

She enjoyed a stellar season in 2022, recording 37 straight wins, but faltered last year, with her 75-week run as number one ending in September.

Swiatek, 22, then lost only one 13 matches to finish the year on a high and followed up by winning all five of her singles at the United Cup last week.

Aryna Sabalenka

The 2023 Australian Open champion looked on course to finish the year on top of the world rankings until Swiatek pipped her by winning the WTA Tour finals.

The consistent Belarusian, who came from a set down to beat Elena Rybakina in the final 12 months ago, boasted a fine record at the majors last year.

She reached the semi-finals in Paris and at Wimbledon before losing to Coco Gauff in the final of the US Open.

The powerful 25-year-old was the first player since Serena Williams in 2016 to reach at least the semi-finals at all four Slams in a single season.

Sabalenka reached the final at last week's Brisbane International, losing to Rybakina.

Elena Rybakina

The Russian-born Kazakh came close a year ago to adding the Australian Open crown to her 2022 Wimbledon title, losing to Sabalenka in three sets.

The world number three started the year in style, dropping just three games in beating Sabalenka in the Brisbane final, where lost only 15 games in five matches.

"For sure it gives me confidence," she said about her Australian Open prospects. "I'm playing well now, so hopefully I continue."

Naomi Osaka

The Japanese fan favorite knows her way around Melbourne Park, lifting the winners' Daphne Akhurst Memorial Cup in 2019 and 2021, but she is something of an unknown quantity this year.

The former world number one has admitted she almost gave up on tennis but is now back in love with the sport.

The 26-year-old stepped away from the game in September 2022, citing mental health concerns. She gave birth to daughter Shai and said she did not watch any tennis until last year's Wimbledon.

Osaka will be unseeded after dropping to 833 in the world but no top player will want to face her in the first round when the draw takes place on Thursday.

Emma Raducanu

Britain's Emma Raducanu stunned the tennis world when she won the US Open in 2021 as a qualifier but only on one other occasion has she reached the fourth round of a Grand Slam.

The 21-year-old has plummeted to 299th in the world after an eight-month layoff with ankle and wrist injuries.

Raducanu, who has a high profile despite her relative lack of success, took Ukraine's Elina Svitolina to three sets in round two in Auckland last week.

But she is still feeling her way back from injury and will likely regard any sort of run in Melbourne as a bonus.

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