Serena Williams won the Australian Open while two months pregnant, it has emerged, after her publicist confirmed the tennis superstar is expecting her first child.

Williams, who will return to the world No.1 ranking next week, set the tennis world abuzz by briefly posting a selfie earlier Thursday morning (AEST) that appeared to announce the pregnancy.

The 35-year-old posted a side-on Snapchat photo of herself in a bathing suit displaying a protruding stomach with the caption “20 weeks”.

The photo was later deleted and the speculation was not confirmed until several hours later when Williams’ representative Kelly Bush Novak released a short statement saying: “I’m happy to confirm Serena is expecting a baby this Fall.”

She said Williams plans to sit out the rest of the 2017 season and return to competition in 2018.

The news of her impending birth means Williams would have been experiencing the early effects of pregnancy when she won her record 23rd Grand Slam title at the Australian Open in January.

The Snapchat photo, since deleted, has set the tennis world abuzz.

Her victory over older sister Venus broke a tie with Steffi Graf for the most Grand Slam singles championships in the sport’s modern era. Serena Williams has not played since.

Williams, the highest-paid female athlete in the world, announced her engagement to Reddit co-founder Alexis Ohanian in December.

Serena Williams with fiance Alexis Ohanian. Photo: Instagram

The Snapchat photos prompted an overwhelmingly positive response from the tennis world, with US Open organisers publicly congratulating Wiliams on Twitter.

Wiliams photo post is reminiscent to the Instagram announcement made by her friend, music star Beyonce, in February.

.@serenawilliams will have a new pride & joy to hug and call her own soon! Congratulations on the exciting baby announcement! #USOpen pic.twitter.com/NXxlY4vC6q

— US Open Tennis (@usopen) April 19, 2017

Sharapova slight

The post also comes on the day that Wiliams’ long-time rival Maria Sharapova is celebrating her 30th birthday.

Williams and Sharapova are not only fierce competitors on the court, but have been embroiled in an off-court animosity in recent years – rumoured to involve a mutual boyfriend.

In a 2013 Rolling Stone interview, Williams alluded to Sharapova’s “boring” expressions of happiness in her new relationship with a man she described as having a “black heart”.

It was widely accepted the boyfriend in question was Grigor Dimitrov, a rumoured former flame of Williams.

Despite public denunciations and apologies from both players, their rivalry remains fiery.

After two early wins in 2004, Sharapova had not defeated Williams in their 18 encounters since, including three Grand Slam finals and an Olympic Games gold-medal match.

Other women have left the tour to have children and returned at a high level, though none has done so at Williams’ age.

Belgian former world No.1 Kim Clijsters retired and had a child before coming back at age 26 and winning three grand slam titles as a mother.

Australians Evonne Goolagong and Margaret Court also won grand slam titles after having children.

Former No. 1 Victoria Azarenka of Belarus, 27, missed most of the 2016 season to have a baby and is expected to return to the tour this summer.

Williams, who has played professionally for two decades, first gained the No. 1 ranking in 2002 and has held that spot for more than six years in total during her career.

She withdrew from the BNP Paribas Open and the Miami Open last month citing a knee injury.

At an age when most tennis professionals have already retired, Williams still dominates the women’s tour.

Sister Venus, 36, has won seven grand slam singles titles.

– With agencies