Kate Middleton faced serious fashion competition from Lady Amelia Windsor and Princess Eugenie during Queen Elizabeth II's birthday celebration at St. Paul's cathedral in London Friday. The 20-year-old stole the show in black Chanel outfit, while Princess Eugenie stunned in an Eponine red dress.

The Duchess of Cambridge wore a powder blue coat dress with a white lace overlay by Catherine Walker and a cream Jane Taylor hat. However, this time Middleton failed to leave her fashion mark as the young Windsor grabbed all eyes with her pleated dress with tweed sleeves. The granddaughter of the queen's cousin Prince Edward the Duke of Kent, completed her look with skyscraper shoes and a quilted yellow bag.

On the other hand, Princess Beatrice didn't quite make an impression with her fashion choice Friday. She wore an elaborate patterned black and white coat from Burberry, teamed with a cream disc fascinator featuring a large black bow.

queen birthday Britain's Princess Margaret (left), Princess Eugenie (Center) and Princess Beatrice attend a reception at the Guildhall following a service of thanksgiving at St Paul's Cathedral for Queen Elizabeth's 90th birthday in London, Britain, June 10, 2016. Photo: REUTERS/Hannah McKay/Pool

Middleton's outfit cost nearly $21,390, Daily Mail reported, adding that the cream Jane Taylor hat was priced nearly $1,400 while her nude patent heels by Gianvito Rossi cost $712. 

Meanwhile, Zara Tindall — the second-eldest grandchild of Queen Elizabeth II and Prince Philip — kept her look simple in a navy dress with a blue floral pattern.