Two-time champion Victoria Azarenka has withdrawn from the Australian Open because of the ongoing custody battle over her 11-month-old son.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.
The Belarusian joins Andy Murray and Serena Williams in withdrawing from 2018's opening Grand Slam.
Tournament organisers announced in December that she would be given a wildcard entry despite being ranked 201 in the world.