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Ever the joker, the young royal pulled a series of hilarious faces which gave the adorable youngster a serious case of the giggles.
The Prince also showed his soft side, reaching out to stroke the baby's head.
Meanwhile on the pitch, it was a family affair as Harry and his brother Prince William took part in the Audi Challenge Cup.
The Duchess of Cambridge turned up to support her husband and her brother-in-law, and even brought along puppy Lupo who charmed everyone as he bounded around the field.
Harry in particular bonded with the pooch, stroking him and planting a kiss on his head.
Watch: Prince William takes George to meet his sister
It's a little princess!