Ashleigh Barty is hot favourite to win her home Australian Open for the first time when it begins on Monday, but even with Serena Williams absent the world number one faces threats from all angles.

For the first time in a quarter of a century the first Grand Slam of the year will not feature either of the Williams sisters – Serena would have been pursuing a record-equalling 24th major crown but she is not fit.

With defending champion Naomi Osaka still working her way back to top form and fitness after a long break, the 25-year-old Barty has emerged as the clear favourite at Melbourne Park. She is drawn to meet 13th-seeded Osaka in the last 16 should they both get that far.

Like Osaka, Barty was dumped out of the third round of the US Open in September and did not play the rest of last year, returning home to Australia because of the coronavirus pandemic.

Unlike the Japanese former world number one, who pulled out of a Melbourne warm-up tournament saying her “body got a shock” after playing her first matches for four months, Barty appears to be back in the groove.

Barty won the French Open in 2019 and Wimbledon last year but her best performance in Melbourne was reaching the semi-finals in 2020, where she lost to eventual champion Sofia Kenin.

However, she fired a warning to the rest of the Australian Open, claiming the singles and doubles titles at the Adelaide International, and said on Saturday that she was “chomping at the bit to get after it”.

Home expectations are high of the top seed, who faces a potentially tricky first round match Monday against qualifier Lesia Tsurenko, a four-time title-winner on the WTA Tour.

“Always a tough one against a qualifier, particularly someone who has been so successful in the past,” said Barty.

“She obviously knows how to win big matches.”

Osaka, who has vowed to have more fun on court in 2022 after saying last year that she had suffered from depression, launches her title defence against Colombia’s Camila Osorio alsom on Monday.

Halep, Muguruza threaten

Men’s tennis has been dominated by the “Big Three” of Novak Djokovic, Rafael Nadal and Roger Federer, but women’s tennis remains wide open.

Last year’s four Grand Slams were won by four different women – Osaka (Australian), Barbora Krejcikova (French), Barty (Wimbledon) and Emma Raducanu (US).

Osaka and Barty’s early exits at the US Open underlined the unpredictability of the women’s game.

Osaka, a two-time Melbourne champion, went out to eventual New York finalist Leylah Fernandez, who lost in the championship decider to fellow unseeded teenager Raducanu.

Britain’s Raducanu, who is embarking on her first full WTA Tour season, has struggled since her stunning emergence at Flushing Meadows and last month tested positive for Covid-19.

She pulled out of a Melbourne build-up event saying that it was “too soon for me” and the 19-year-old was then thrashed 6-0, 6-1 by Elena Rybakina of Kazakhstan on Tuesday.

As well as Raducanu and Fernandez at Melbourne Park, there will also be another prodigious talent in the form of 17-year-old American Coco Gauff.

But this could be the chance for the older guard to reassert themselves.

Garbine Muguruza, who lost to the American Kenin in the 2020 final, is third in the world rankings behind Barty and big-hitting Aryna Sabalenka of Belarus.

The 28-year-old Spaniard squandered two match points against Osaka last year at Melbourne Park in the last 16 and won the season-ending WTA Finals in Guadalajara.

There is also the re-emergence of another former number one, Simona Halep.

The 30-year-old Romanian, a popular figure within women’s tennis, earlier this month won her first title in 16 months following a bleak run of calf and knee problems.

“After a tough year it’s always nice to have a trophy in my hands,” said the Romanian.

“Physically I’m in the right place, confidence is growing.”