With 23 Grand Slam titles under her belt, Serena Williams is pretty steady under pressure.

But there are claims this morning the American might have accidentally let slip the gender of Meghan Markle’s baby.

During a television interview the tennis star was asked about advice she had for new mothers.

“We put so much pressure on ourselves,” she said.

“My friend is pregnant and she’s like, ‘Oh, my kid is gonna do this’ and I just looked at her and I was like, ‘No, she’s not’.

“I’m like, ‘No you’re not’ and she started laughing.”

Williams and Markle are know to be very close friends.

With royal watchers yearning for any new clues, many have speculated the 37-year-old was talking about Meghan’s child, who is due this month.

Special attention has been placed on the line: “No she’s not.”