The tennis star has since praised George’s skills and said he was a “sweet boy”, as he told reporters at Wimbledon in 2019: “I love to see that they are [the Wales children] into tennis or into sports.”

Federer added that the young heir had a “good swing”, and also spoke highly of Kate and her well-documented fondness for the game.

He said: “His mum has always enjoyed tennis. I hope he’ll stay the same in a few years’ time and this is not just an in-the-moment situation.”

When asked if the rumours were true that he was George’s favourite tennis player, Federer responded: “I think I have a little advantage that I actually spent some time with him, so maybe I’m the only player he’s ever met. Then you have a little head start into who is your favourite player.”

Kate and Prince William have also turned to Federer’s one-time rival Djokovic for some advice on how to get their children into tennis.

Back in 2018, the Serbian asked the couple at the tournament: “How are your children?”, to which Kate replied: “Yeah, very well”. William then said: “Very well thanks, very well… Trying to get a tennis racket in their hand and a football!”

A source said at the time: “She [Kate] says with George just being four he wants to whack a ball, so she was asking what sort of stuff she should be doing.”