The withdrawal of both players was reported by Russian media and confirmed on the official Twitter account of the Australian Open.
Petrova'smother Nadezhda Ilyina, who died in a car accident in the Moscow region on December 7. A successful 400 metre runner, she won a bronze in the 4x400 relay in the 1976 Olympics in Montreal.
She had also held the USSR record in both the 400 metres and the 4x400 metres relay as well as the world record for 400 metres indoors.
"Our condolences to Nadia Petrova who's withdrawn from Ausopen following the tragic loss of her mother," the Australian Open organisers said.