Kate, who recycled the white linen Zimmerman dress that she had recently worn during her trip to Australia, grimaced and clasped her hands to her mouth as she watched Britain's Andy Murray lose against Bulgaria's Grigor Dimitrov, in the men's singles quarter-final match on Wednesday.
The Duchess, 32, and her husband William, 31, looked as if they felt Andy's pain as the tennis star was sent crashing out of the prestigious British tournament.
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The Duchess of Cambridge couldn't contain her excitement
William and Kate joined other spectators in giving Andy a standing ovation, applauding and sadly shaking their heads as the athlete exited the competition.
The Duke and Duchess had turned up early in the day to take their places in the Royal Box, where they also watched the Simone Halep vs Sabine Lisicki game.
Prince George's mum beamed and greeted the Duke of Kent as she arrived. William, meanwhile, happily chatted to Gill Brook, wife of AELTC Chairman Philip Brook, who was seated next to him.
Kate and Prince William applaud Andy Murray
Other stars in attendance on Wednesday included Hugh Grant, Michael McIntyre, Andy's girlfriend Kim Sears, Princess Beatrice and her long-term boyfriend Dave Clark.
Kate's parents Carole and Michael Middleton also made the trip down to London.
Kate's white Zimmerman dress sold out after the Duchess wore it
William and Kate's visit to Wimbledon comes shortly after Kate's younger siblings James and Pippa were also pictured enjoying a day out at the tennis. They watched Lukas Rosol play against Rafael Nadal, who has since exited the competition.
Princess Mary and Prince Frederik of Denmark also courted attention on the same day, as they enjoyed the action from the Royal Box alongside athletes Jonathan Edwards, Denise Lewis and Steve Redgrave.
Kate and Prince William watching the Simone Halep vs Sabine Lisicki game