Serena Williams just revealed that she's 20 weeks pregnant

Serena Williams has shared a picture on Snapchat saying she's 20 weeks pregnant.

One of the greatest tennis players of all time, it means the 35-year-old's days of racking up Grand Slam titles are over for a little while.

The 23-time major winner posted a selfie of a small baby bump with the caption "20 weeks".

The dates would mean she won the Australian Open in January 10 weeks after conceiving.

The news has been confirmed by her team.

She won a Grand Slam while 20 weeks pregnant.

Tennis veteran Brad Gilbert tweeted his congratulations.

The US player didn't drop a set in Melbourne.

People were quick to point out Serena was pregnant when she won the first major title of the year.

Noelle tweeted: "Serena Williams was pregnant when she won her 23rd grand slam tournament at the Australian Open. And did not drop ONE SET. Let that sink in."

Serena hasn't played since then, pulling out of both Indian Wells and Miami, citing a knee injury.

The star is engaged to Reddit co-founder Alexis Ohanian, 33.

Serena posted a picture of her with fiance Alexis Ohanian earlier this week.

A few days ago the tennis champion also shared a post of her friend Kelly Rowland's new book on Instagram - all about parenthood.

See Serena's post about Kelly Rowland's book.

There was some confusion about her announcement from the official Twitter account of the women's tour, the WTA, on Wednesday.

They tweeted congratulations to Serena before deleting the post.

It's not only good news for Serena, but it's also good news for the rest of the women's tour too.

Their chances of winning the sport's biggest titles have just significantly increased.

Serena beat her sister Venus to lift the first major title of the year in Melbourne, Australia