Kate Middleton, who loves to accept challenges, stunned fans as she Tuesday joined a team of pupils being supported by Dame Kelly's trust at its base in Bath, with the former sports star on the other team.
The Princess of Wales finished second best after taking on the Olympic champion at a game of bean-bag noughts and crosses. Kate did her best but Dame Kelly's team won twice. After the first victory, the track and field star held her arms aloft and admitted she is "slightly competitive".
The Princess joked: "You would never have guessed."
Delightful pictures of Kate's outing were posted on The Prince and Princess of Wales's official social media accounts.
Kate put her elegance on display as as she rocked bright yellow blazer from LK Bennett, which she paired with a white t-shirt and matching trousers and trainers.
With her latest stunt, Prince William's wife seemingly teased Meghan Markle who attracted spotlight with her recent outing with the Hollywood stars.
It comes after the Duchess of Sussex began her US relaunch this week as she posed with youngsters on a charity visit and dined with Hollywood royalty before preparing to accept a 'racial inequity' award on Tuesday (tonight).
Fresh from her Eurovision cameo appearance in beautiful blue gown - the Princess debuted a mustard yellow blazer for the latest outing.
The princess later sat down to chat to the pupils, all girls aged from 11-13, who spoke about their experiences at school, home life and the benefits of being mentored by a sports star.