Streetwise young pretenders called Bratz have knocked Barbie from her long-standing position as the best selling fashion doll in the UK.
The Bratz dolls are designed to be more funky than Barbie
It is the first time Barbie has had to relinquish the title since retail firms started monitoring sales a decade ago.
Sales of Bratz dolls - only released in the UK three years ago - are up 130% on last year, said the makers, after they captured girls' "hearts and minds".
Barbie remains number one in the wider sector, including dolls' clothing.
But the Bratz dolls - among them Yasmin, Jade, Sasha, Meygen and Fianna - are designed to be more streetwise and funky than Barbie.
The toys, which sell for about £22 each, appeal to girls aged eight and above with the slogan: "The girls with a passion for fashion".
Barbie - who will celebrate her 45th birthday this year - has a target audience from age three upwards but is battling against perceptions that she is outdated.
Barbie, first released in 1959, has been a favourite in the UK for years
She "broke up" with long-term boyfriend Ken earlier this year - ditching him for surfer Blaine - in a bid to revitalise her fortunes.
But retail audit company NPD said Bratz had snatched a 41.5% share of the UK fashion doll market in August to outsell Barbie.
The firm said it was the first time Barbie, released by makers Mattel in 1959, had dropped from the country's top spot since 1994.
Nick Austin, chief executive of Bratz's UK distributors, said: "Bratz came from nowhere and have captured the hearts and minds of a new generation of girls."
He said it was a "real David versus Goliath" contest where an iconic brand had been toppled by a brand "more relevant to today's fast-changing consumer".
A spokesman for Mattel said: "Barbie continues to connect with girls and mums all over the world.
"She continues to outsell her nearest competitor by more than two-to-one in unit sales of dolls, clothes and accessories (in the) year to date, and is the number one girls' brand in the world with more than $3.6bn (£2bn) in annual retail sales."