A slip of the tongue has fans convinced Serena Williams revealed the gender of Meghan's royal baby

Cape Town – Serena Williams may have let slip a significant detail about Prince Harry and Meghan's unborn baby.

Fans were quick to point out that the tennis pro may have unintentionally revealed that the Duke and Duchess of Sussex are expecting a girl during an interview with E! News.

The accidental slip-up came when Serena was asked what advice she would give to new moms and discussed the immense pressure women put on themselves.

"Accept mistakes and don't expect to be perfect. We put so much pressure on ourselves," she initially answered.

She then continued: "My friend is pregnant. And she was like, 'My kid's gonna do this,' and I just looked at her and was like, 'No, she's not… No, you're not.'

Of course, there is no way of telling which friend Serena was speaking about. However the mom-of-one quickly tried to save herself by correcting "she's" to "you're".

CLICK HERE TO WATCH THE VIDEO CLIP.

As bets as to what the royal couple are expecting roll in, Harry and Meghan have maintained that they don't even know if it's a boy or girl – even though Meghan opted not to open her gifts at her baby shower in NYC because it would reveal the sex of the baby.

READ MORE: Here’s why Duchess Meghan didn’t open her baby shower gifts

Meanwhile, if Meghan does give birth to a girl bookies are convinced she will be named after Princess Diana.

According to a report by Mirror in March, the name Diana was the clear favourite baby name, with odds of 10:1. The name Alice came in at a close second at 12:1, while Alexandra also made an appearance at 16:1.

READ MORE: Punters predict the Duke and Duchess of Sussex will name their baby Diana