(AFP) - Emma Raducanu's extraordinary US Open triumph on Saturday led to an explosion of joy in Britain, with Queen Elizabeth II leading the celebrations as the 18-year-old qualifier made tennis history in New York.

Raducanu beat 19-year-old Canadian Leylah Fernandez 6-4 6-3 to become Britain's first women's Grand Slam singles champion since Virginia Wade at Wimbledon in 1977, and the first player to win a major after coming through a qualifying tournament.

"I send my congratulations to you on your success," the Queen said. "It is a remarkable achievement at such a young age, and is testament to your hard work and dedication."

The Queen's letter gave the teenager an indication just how widespread the acclaim for her incredible triumph has been in Britain.

Admitting she was honoured to receive contact from the Queen, Raducanu told the BBC: "It meant everything to get a message from Her Majesty.

"She's such a great inspiration and role model for the whole country so, to have a note from her, I was extremely honoured and very, very grateful that she took notice of my tennis.

"I can't believe it. I'm maybe going to frame that letter or something."

Raducanu's win even managed to knock football superstar Cristiano Ronaldo's two goals on his return to Manchester United off Sunday morning's British newspaper front pages.

The Express called it "Absolutely Emm-ense!" while the Telegraph proclaimed: "She did it!"

Social media caught fire after Raducanu sealed the win with an ace.

Former England footballer Gary Lineker broke off from presenting the Premier League highlights programme "Match of the Day" on BBC TV to post: "First time in my life I've ever tweeted whilst on air but my goodness what a performance, what a triumph, what an amazing young woman."

Prime Minister Boris Johnson tweeted: "What a sensational match! Huge congratulations to Emma Raducanu. You showed extraordinary skill, poise and guts and we are all hugely proud of you."

Raducanu's only previous Slam appearance, at Wimbledon in July, ended when she pulled out of her fourth-round match with breathing difficulties.

"Look at that bounce back @EmmaRaducanu US Open champion, amazing. Congratulations," tweeted England and Manchester United footballer Marcus Rashford, who had offered support to Raducanu after her Wimbledon exit.

Formula One world champion Lewis Hamilton said: "It has been incredible to see her rise, the focus she has and the sheer determination.

"She is a sweet person, too, so the UK can be proud of her and I am super-proud of her and I can't wait to see what she does next. She is an inspiring figure."

Raducanu was born in Canada to a Chinese mother and Romanian father, but grew up in Bromley in suburban south London after moving to England at the age of two.

- 'It's mind boggling' -

At her former tennis club, Parklangley, members gathered in front of TVs on Saturday night to roar her to victory.

"I'm speechless. I'm sore and hoarse from screaming," said her former coach Suzanne Williams.

Former British number one Tim Henman, who was courtside in New York, said: "She will win more of these, she is that good. This is not some flash in the pan or fairytale. She is playing top-five tennis."

Australian Grand Slam winner Pat Cash told BBC radio that a qualifier winning a major is "something I never could have believed would happen. It's mind boggling."

And tennis great Martina Navratilova tweeted: "A star is born -- Emma Raducanu makes history... and she is just getting started. And will never have to qualify again:)"

In China, where the match took place in the early hours of Sunday, Tencent published an article with pictures of Raducanu visiting China as a child.

"An ethnic Chinese won the US Open" it trumpeted. "She claimed that her motivation (or power) comes from her Chinese mother!"

© Agence France-Presse