Duchess of Cambridge Kate Middleton threw all pretenses of a dainty royal aside when she took to the high seas today in a battle royale against her husband, Prince William.

Dressed casually in skinny jeans, a nautical striped shirt and blazer, Kate, 32, defeated William, 31, not once but twice while captaining an America's Cup yacht in Waitemata Harbour off the coast of Auckland, New Zealand, where the royals are on a 19-day tour.

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"We were sabotaged," William joked after the race.

William sailed with Team New Zealand manager Grant Dalton, while Middleton raced to victory with Team New Zealand skipper Dean Barker.

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"We pretty much had her on the wheel the whole time," Raynor Haagh, a crew member aboard the yacht with Kate, told ABC News.

Prince William, meanwhile, told his teammates they "had to make sure we win" but fell short against his wife, who has proven her athletic prowess in other royal engagements, from the volleyball court to the lacrosse field.

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"We've got to make sure we win or do whatever it takes," crew member Brad Moss said, recalling the prince's message to the crew. "Unfortunately, that wasn't the end result today."

Kate's win in the waters off New Zealand evened the scoreboard between her and William when it comes to nautical races. Three years ago, while the royals were on a tour of North America, it was William who emerged victorious in a Dragon Boat race in Canada.

After the race, the royals caught the short flight back to Wellington, where their 8-month-old son, Prince George, the star of a play date on Wednesday, remained with his nanny.

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