Tennis legend Evonne Goolagong Cawley believes Serena Williams will join her in one of the sport's most exclusive clubs with a momentous Australian Open triumph as a doting mother.

Goolagong Cawley, fellow Australian all-time great Margaret Court and Belgian Kim Clijsters are the only three mothers in half a century of professional tennis to have won grand slam singles titles.

But Williams is less than seven weeks away from becoming the fourth, according to Goolagong Cawley.

"I think she will," the former world No.1 told AAP.

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"I hope so because she's got so much talent and so much in her to win more tournaments.

"I know that from my own experience, after I had my daughter Kelly, I felt great. I just wanted to get back on that court.

"I'm sure she's feeling the same way."

Williams' long-time coach Patrick Mouratoglou last week cast doubt on the 23-times grand slam champion's appearance at Melbourne Park next month, saying "we will take a decision regarding Australia".

"Serena is getting ready for 2018. She is practising and getting back in shape. I will be joining her soon in Florida," Mouratoglou said.

"We will see how her body is reacting and how her tennis level is."

Williams only gave birth to her first child, daughter Alexis Olympia, in September, leaving just four months to prepare for the first major of the new year starting on January 15.

But Australian Open director Craig Tiley on Wednesday said Williams was "very likely" to defend her title.

"She's got her visa, she's entered, she's practising - she probably just needs a little more space for her entourage," Tiley said.

"There's no question that she'll be ready, in our view."

Williams only revealed in the weeks after beating sister Venus in this year's final that she was pregnant when she won her record seventh Open crown in Melbourne in January.

Now Goolagong Cawley believes Williams - at 36 and a five years older than when Court broke new ground in women's sport by winning the 1973 Australian Open as a new mother - will continue to defy history.

Goolagong Cawley was "only" 26 when she won the 1977 Open as a mother, the same age as Clijsters when she lifted the US Open trophy after having her first child.

"She won it (this year) while she was pregnant, so, yes, she is capable," Goolagong Cawley said of Williams.

"I felt great after having Kelly. I won in Australia in '77 and in '80 (when I won Wimbledon). I felt fantastic."