Battle of the expressions! Kate and Kim can't hide their frustration and elation as Andy Murray wins his Wimbledon quarter final clash
- Duchess of Cambridge in royal box at Wimbledon to watch quarter finals
- Saw Andy Murray take on Canadian Vasek Pospisil
- Like Andy's wife, Kim, she got into the game heart and soul
- Cheered Brit on and looked disappointed if he missed a shot
- Delighted to watch him win
From frustration to elation, every hit and miss Andy Murray played in his Wimbledon quarter final match was etched over his wife Kim's face.
And it wasn't just Kim who was passionate about supporting her man. The Duchess of Cambridge also got into the match and was just moved by every point won or lost by the British number one.
Like many others watching at home and on centre court, Kate and Kim couldn't contain their emotions as they watched Andy take on Canadian Vasek Pospisil to win a place in the semi-finals.
Oooh! The Duchess of Cambridge grimaces as Andy Murray misses a shot, left, in an expression mirrored by his wife Kim, right, who looks like she can't believe it
Ahh! Kate is open-mouthed like Kim as tensions rise in Andy's quarter final clash
Something funny? The pair both got the giggles during their time on centre court
He did it! Kate and Kim rise to their feet and applaud as Andy clinches the match
For every double fault or out ball that Andy struck, Kate was as disappointed as artist Kim and wasn't afraid to show it.
Just like Kim, mother-of-two Kate, 33, cheered and clapped every time Andy hit a winning shot, although she refrained from Kim's penchant for punching the air and screaming 'come on!'
Both were delighted with beaming smiles when he secured a victory in straight sets 6-4 7-5, 6-4.
Tennis fan Kim has become well-known for her passion for tennis - just like her mother-in-law Judy.
Getting highly strung in matches has led to Kim getting into hot water in the past when she has been captured swearing at Andy's opponents and telling them to 'f***ing have it' when he delivers an non-returnable shot.
Hair flick: Both famous for their bouncy, long locks, they needed to pull their hair off their faces on occasion
Come on Andy! Kate cheers and claps like Kim as Andy takes the lead winning the first set
Yes! The Duchess gets to her feet to applaud while Kim punches her fist in the air to celebrate a winning shot
But Andy revealed in his BBC column that it's not just his clashes that Kim gets animated about. She's such a fan of the sport and loves backing the Brits that she got excited when watching Heather Watson take on Serena Williams last week.
Like many people watching at home, she was screaming Heather on through the TV, getting their border terriers Maggie May and Rusty worked up in the process.
'I don't really jump up and scream when I'm watching because of the dogs - Kim was doing that and the dogs were going crazy,' he said of viewing Heather's closely fought match.
As a member of the royal family, Kate might be expected to show some more decorum when on public duty.
Concern: Both looked tense at moments in the game when Canadian Vasek Pospisil played well
Diamonds (and a sapphire) are a girls' best friend: The pair show off their bling engagement rings as they push their hair behind their ears
Preening: Putting their hair into place again as a breeze passed through centre court
But like Kim, sports mad Kate can't hide her frustration or delight when she cares about the outcome of a match - and her feelings became elevated when caught up in the atmosphere on centre court.
Sports psychologists describe the behaviour as 'disinhibition'.
In a paper published on the subject, Professor of Psychology Susan Krauss Whitbourne Ph.D. writes: 'Other concepts help explain why fans do what they do during games. Fans who actually attend games regularly display the social psychological phenomenon of disinhibition.
'They shout, yell, stand up, cheer, and high five strangers all around them. Even people who are ordinarily reserved and shy will explode in bursts of exhibitionism when surrounded by other people engaging in the same unrestrained excitement.'
Andy now progresses to the semi finals on Friday.
Kate and Kim bite their lips in anticipation of the match that could see Andy through to the semis
Accessorising: While Kate travelled light with a clutch, left, Kim carried her Aspinal tote bag
Both look deep in thought at this stage in the game, perhaps wondering if Andy can win
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