Serena Williams has posed nearly naked for the cover of Vanity Fair's August issue showcasing her growing baby bump.

The tennis star - who is now six months pregnant with fiancé and Reddit co-founder Alexis Ohanian - revealed she hopes to be back on court as soon as January 2018, telling the magazine her "story isn't over yet".

The 35-year-old added her pregnancy still "doesn't seem real, I don't know why.... Am I having a baby?"

Williams told of her shock at finding out she was pregnant, saying she "did a double take and my heart dropped".

The former world number one said, of her initial thoughts: "'Oh my God, this can't be – I've got to play a tournament. How am I going to play the Australian Open?'"

Williams went on to beat her sister, Venus, to win in Melbourne for the seventh time.

The seven-times Wimbledon champion's cover photo shoot comes after former tennis world number one John McEnroe was widely criticised for comments he made about Williams in which he appeared to belittle her achievements.

After describing Williams on US radio as the greatest female player of all time, McEnroe was asked why he had not simply said greatest player.

McEnroe also said that if Williams played on the men's circuit she would struggle to make it into the top 700.

Speaking about his comments the 58-year-old said: "I felt the need, however unfortunately, to defend myself and say what I really felt, which is about what I think she would be.

"I've got a solution. Solve the problem, and I'm sure the men would be all for this – the men and women play together. And then we don't have to guess."

Williams later responded to McEnroe on Twitter, telling him to "please keep me out of your statements that are not factually based".

Williams' pose follows in the footsteps of Demi Moore, who made the naked baby bump stance famous on Vanity Fair's cover in August 1991.

Since then, numerous celebrities have been pictured showing their bumps.

In February, Beyoncé took to Instagram to announce her pregnancy, baring her stomach and writing that she had been "blessed two times over", indicating she was expecting twins.

In a style similar to Williams, actress Natalie Portman graced Vanity Fair's cover in January, again showcasing her bump.

In June 2016, Alanis Morissette mimicked the pose while floating in a swimming pool.

While in June 1999, Cindy Crawford graced the cover of W magazine when she was seven-months pregnant with her first child.

Cindy Crawford poses for the June 1999 cover of W magazine. Credit: W magazine/Michael Thompson