The Queen has led the congratulations to Emma Raducanu after the 18-year-old clinched the US Open title with a stunning victory in New York.
Raducanu beat fellow teenager Leylah Fernandez 6-4 6-3 to end Britain's 44-year wait for a women's Grand Slam singles champion.
"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."
In a statement, the monarch added: "I have no doubt your outstanding performance, and that of your opponent Leylah Fernandez, will inspire the next generation of tennis players."
UK 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."
'A star is born' - praise pours in for Raducanu
Virginia Wade, who was present at Arthur Ashe Stadium to witness Raducanu's win, was the last British woman to win a Grand Slam singles title - at Wimbledon in 1977.
In an unprecedented run Raducanu became the first qualifier to win a major title and has done so without dropping a set.
"A star is born," tennis legend Martina Navratilova said. "Emma Raducanu makes history and she is just getting started."
Former Wimbledon champion Pat Cash described Raducanu's success as "mindboggling".
"This is something I never could have believed would happen," the Australian said on BBC Radio 5 Live.
"I think I am going to wake up. It is so unbelievable. It is flabbergasting to see this performance."
Raducanu won the title with a classy performance in a high-calibre match against Canada's Fernandez that lasted almost two hours.
By the end it appears as if it had the UK gripped with many people tweeting to ask for Match of the Day to be delayed.
Presenter Gary Lineker tweeted: "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."
More to follow.