Two-time champion Victoria Azarenka has withdrawn from the Australian Open because of the ongoing custody battle over her 11-month-old son.
Azarenka cannot leave California with Leo until the dispute is resolved.
The former world number one, 28, has not played since Wimbledon last year and will be replaced in Melbourne by Australian wildcard Ajla Tomljanovic.
Tournament organisers announced in December she would be given a wildcard entry despite being ranked 201 in the world as a result of her lack of tournament play.
But Australian Open director Craig Tiley said on Monday: “It’s unfortunate ‘Vika’ is unable to travel to Australia this year. The Australian Open is her favourite tournament and she’s looking forward to returning to Melbourne next year.”
Former champions Rafael Nadal and Novak Djokovic also remain doubts for the tournament.