Princess Kate scolded by Roger Federer after making a Wimbledon cardinal sin

Seen in a YouTube video, Princess Catherine was told off by ball girl Mollie over her Wimbledon mistake.

The Princess of Wales appeared to meet her match during a recent trip to Wimbledon.

While shooting a behind-the-scenes film for the tennis tournament’s YouTube channel about this year’s carefully selected ball boys and girls, Kate found herself in trouble.

Starring alongside tennis champion, Roger Federer, the 41 year old princess was standing court side with a friendly ball girl as the retired tennis legend played and caught a stray ball as it headed out of bounds.

The catch appeared impressive and earned a “good catch” from ball girl Mollie but it didn’t win over Federer who quickly called out the Princess for her seeming lack of tennis knowledge, “Are you allowed to do that? In Australia, they would catch it, but in Wimbledon they don’t,” he cheekily quipped.

Unsure of whether she had made a mistake, Kate turned to Mollie asking whether she was allowed to catch it and the ball girl explained, “You are not meant to catch it. You are meant to let it bounce and then get it, but good catch.”

However, despite making the mistake, Kate went on to impress the tennis star with her skills and beat Federer with a cracking shot during a friendly match. “I think it was on the line. Amazing,” Federer, also 41, congratulated his royal opponent.

Elsewhere in the match, Kate took a moment to ask the retired tennis star for some pointers on the court: “Any tips on my serve at the same time would be very helpful,” she joked.

Catherine, Princess of Wales and Wimbledon champion Roger Federer join a ball boy and girl practice the All England Lawn Tennis Club, Wimbledon. Photo / Getty Images

But Federer appeared to think she didn’t need any and instead gave her an elite compliment: “The serve looks good.”

The two came together to highlight the world of ball boys and girls for the upcoming tournament and received their own training from Mollie – an official Wimbledon ball girl.

The four-minute, 15-second long video ends with the pair visiting an indoor training centre where Kate gushed over the “incredible” ball boys and girls that have been chosen for this year’s tournament.