British teenager Emma Raducanu arrived in New York last month with a ranking of 150th, just one Grand Slam appearance to her name and a flight booked to head out of town after the US Open's preliminary rounds in case she failed to win her way into the main tournament.

And there she was in Arthur Ashe Stadium Saturday, cradling the silver trophy to complete an unlikely – indeed, unprecedented – and surprisingly dominant journey from qualifier to major champion by beating Canadian teenager Leylah Fernandez 6-4, 6-3 in the final.

Until three months ago, Raducanu had never played in a professional tour-level event, in part because she took 18 months off for a combination of reasons: the pandemic and her parents' insistence that she complete her high school degree.

She is the first female qualifier to reach a Grand Slam final, let alone win one. She captured 10 matches in a row at Flushing Meadows – three in qualifying, seven in the main draw – and is the first woman to win the US Open title without dropping a set since Serena Williams in 2014.

Raducanu, who was born in Toronto and moved to the UK with her family at age 2, also is the first British woman to win a Grand Slam singles trophy since Virginia Wade at Wimbledon in 1977. Queen Elizabeth II sent a congratulatory note, hailing the victory as a "remarkable achievement at such a young age."

There were more firsts, too, emblematic of what a rapid rise this was. For example, Raducanu is the youngest female Grand Slam champion since Maria Sharapova was 17 at Wimbledon in 2004.

This was the first major final between two teens since Williams, 17, beat Martina Hingis, 18, at the 1999 US Open; and the first between two unseeded women in the professional era, which began in 1968.

Fernandez, whose 19th birthday was Monday and who is ranked 73rd, had not made it past the third round before. This was only her seventh major tournament.

As tears welled in her eyes after the final, she told the Arthur Ashe Stadium crowd: "I hope to be back here in the finals and this time with a trophy – the right one."

Both she and Raducanu displayed the poise and shot-making of veterans at the US Open –  not two relative newcomers whose previous head-to-head match came in the second round of the Wimbledon juniors event just three years ago.

Raducanu's only previous Grand Slam tournament came at Wimbledon, where she stopped playing during the fourth round because of trouble breathing. That was in July when Raducanu was ranked outside the top 300 and unknown.

And now? She will rise into the WTA's top 25. She earned $2.5 million. She is famous in the UK and the world over. She is now, and forever, a Grand Slam champion.

How quickly everything has changed.