Barty to return to action in Adelaide, Nadal and Osaka in Melbourne

Ashleigh Barty will return to action for the first time in four months at Adelaide in January while Naomi Osaka and Rafael Nadal kickstart their Australian Open build-up in Melbourne, officials said Friday.

Barty hasn't played since a shock third-round loss at the US Open in September, but the Australian still finished 2021 as world number one after a season in which she won five titles.

The reigning Wimbledon champion headlines in Adelaide International field that boasts nine of the world's top 10 women, including Iga Swiatek, who will be defending her title.

Former world number ones Garbine Muguruza, Karolina Pliskova and Victoria Azarenka are also entered for the January 2-9 event, along with world number two Aryna Sabalenka.

The only top 10 player missing in Adelaide will be seventh-ranked Estonian Anett Kontaveit.

Defending Australian Open champion Osaka, who has slipped to 13 in the world, will play at the Melbourne Summer Set event from January 3-9, which features simultaneous women's and men's tournaments.

She will be joined by US Open champion Emma Raducanu, whose form has slumped since her shock win at Flushing Meadows.

Others on the Melbourne bill include Simona Halep, Elise Mertens and Anastasia Pavlyuchenkova, the top-ranked player at 11.

US great Serena Williams, who is marooned on 23 Grand Slam titles -- one short of the all-time record held by Margaret Court -- has pulled out of the Australian summer, saying she was not "where I need to be physically".