The Duchess of Cambridge has been limbering up for her role as Olympic ambassador for six months now and on Thursday she finally stepped up to compete.
Kate was game for a laugh as she took part in a table tennis match at Bacon's college in Rotherhithe, London.
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Although she was dressed for the beautiful summer day in a pretty checked dress and wedge shoes, the Duchess gave her all.
Later, she even kicked off her heels to get on the mats for a spot of Judo.
Accompanied by Princes William and Harry, Kate was supporting the launch of a new sports project in south east London that aims to train the next generation of sports coaches.
Not wanting to be outdone, the princes also got involved in the physical challenges.
More used to Polo, William had mixed fortunes when he joined a group of youngsters for a penalty shoot out.
After missing the mark, the royal jokingly blamed his lack of prowess on his footwear, telling one of the youngsters it was "obviously" his loafers that were the problem.
Meanwhile, Harry tried his hand at shooting hoops with the centre's young basketball players.
When the Duke of Cambridge took to the podium to make a light-hearted speech, he mentioned his brother's famous cheating episode against sprinter Usain Bolt, and praised his former hockey player wife's physical prowess.
"Watching me on the football field is never a pretty sight - the expression giraffe on ice springs to mind. However, it is marginally less embarrassing than seeing my brother cheat his way to becoming the fastest man on the planet," he joked.
"Catherine, on the other hand, with a tennis racket or a hockey stick is something to behold and be aware of."
In the afternoon, the trio were due at Buckingham Palace to watch the Olympic torch go by on the eve of the Games.
The Duchess had been expected to meet a torchbearer whom she nominated especially for the occasion after hearing how he jumped into a river to save a drowning man.
Jon Sayer, 33, a volunteer with the Scouts like Kate, told HELLO! that carrying the flame would be "absolutely incredible".