It was only a month ago that Kate Middleton was providing hilarious zingers about Prince William's ambition to run a marathon.

And now it seems the Duchess of Cambridge has decided to take on her husband and brother-in-law, Prince Harry, in a race to be crowned Britain's best 'royal runner'.

Kate Middleton and Prince William | ELLE UKpinterest
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On Sunday, the trio raced a 50-metre sprint at London's Queen Elizabeth Olympic Park to promote their mental health campaign, Heads Together.

Kate Middleton, Prince Harry, Prince William | ELLE UKpinterest
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Kate Middleton and Prince William race | ELLE UKpinterest
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Cheered on by 150 volunteers of the charity – who are currently training for April's 2017 Virgin Money London Marathon – footage of the relay run shows Harry sprinting off ahead of his family members to take first place, while his brother takes second and Kate Middleton follows shortly behind.

Kate Middleton running | ELLE UKpinterest
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The Duchess – who wore on-trend red puffa jacket and jeans for the race – was spotted embracing her husband shortly after the race.

Prince William and Kate Middleton run race | ELLE UKpinterest
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According to news.com.au, Prince William mentioned a bad hamstring might be the reason for him losing the race while the women's marathon world-record holder Paula Radcliffe allegedly joked shortly after the race that the second-in-line to the throne should have been disqualified for straying into Kate's running lane.

Prince Harry, Prince William and Kate Middleton run | ELLE  UKpinterest
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Prince Harry's appearance at the race comes days after he was spotted out on a date in London with girlfriend, actress Meghan Markle.

As an avid sportswoman herself, we wonder if Meghan would've have beaten her royal beau in the race...

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Katie O'Malley
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Katie O'Malley is the Site Director on ELLE UK. On a daily basis you’ll find Katie managing all digital workflow, editing site, video and newsletter content, liaising with commercial and sales teams on new partnerships and deals (eg Nike, Tiffany & Co., Cartier etc), implementing new digital strategies and compiling in-depth data traffic, SEO and ecomm reports. In addition to appearing on the radio and on TV, as well as interviewing everyone from Oprah Winfrey to Rishi Sunak PM, Katie enjoys writing about lifestyle, culture, wellness, fitness, fashion, and more.