NEW YORK (AP) — 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 U.S. Open’s preliminary rounds in case she failed to win her way into the main tournament.

And there she was in Arthur Ashe Stadium on 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.

“You say, ‘I want to win a Grand Slam.’ But to have the belief I did, and actually executing, winning a Grand Slam,” Raducanu said, “I can’t believe it.”

Who could?

It’s all so improbable.

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

“My dad is definitely very tough to please,” the 18-year-old Raducanu said with a smile Saturday evening. “But I managed to today.”

She is the 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 U.S. Open title without dropping a set since Serena Williams in 2014.

Raducanu, who was born in Toronto and moved to England 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 U.S. Open; 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, was asked during a pre-match interview in the hallway that leads from the locker room to the court entrance what she expected Saturday’s greatest challenge to be.

“Honestly,” she responded, “I don’t know.”

Fair. Neither she nor Raducanu could have.

This was only Fernandez’s seventh major tournament; she hadn’t made it past the third round before.

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.”

Moments later, she asked for the microphone so she could address the 23,703 spectators again on the anniversary of 9-11.

“I just want to say that I hope I can be as strong and as resilient as New York has been the last 20 years,” said Fernandez, born a year before the terrorist attacks. “Thank you for always having my back. Thank you for cheering for me.”

Both she and Raducanu displayed the poise and shot-making of veterans at the U.S. 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.

The talent and affinity for the big stage both possess is unmistakable.

One of the significant differences on this day: Fernandez put only 58% of her first serves in play and finished with five double-faults, helping Raducanu accumulate 18 break points.

“I, unfortunately, made one too many mistakes in key moments,” Fernandez said, “and she took advantage of it.”

Raducanu broke to go up 4-2 in the second set, held for 5-2 and twice was a point from winning the title in the next game. But under pressure from Fernandez, she let both of those opportunities slip away by putting groundstrokes into the net.

Then, while serving for the match at 5-3, Raducanu slid on the court chasing a ball to her backhand side, bloodying her left knee while losing a point to give Fernandez break chance. Raducanu was ordered by chair umpire Marijana Veljovic to stop playing so a trainer could put a white bandage on the cut.

So what went through Raducanu’s mind during that delay of more than four minutes at a critical juncture?

“I was really trying to think what my patterns of play were going to be, what I was going to try to execute,” she said. “Going out there facing a break point after a … disruption isn’t easy. I think I managed, for sure, to really pull off the clutch plays when I needed to.”

As if she’d been there before, Raducanu saved a pair of break points after the resumption, then converted on her third chance to close it out with a 108 mph ace. She dropped her racket, landed on her back and covered her face with both hands.

Eventually, she made her way into the stands to celebrate with her coach and others.

“That’s something that you always think of, you always work for,” she said.

Fernandez’s group — including two sisters and Mom but not Dad, who stayed home in Florida, where they moved after her early success in the juniors several years ago — was in the guest box on the opposite end of the court, the one assigned to the higher-ranked player.

That’s a status Fernandez was unaccustomed to as she beat four seeded women in a row, each in three sets: defending champion Naomi Osaka and 2016 champ Angelique Kerber, No. 2 Aryna Sabalenka and No. 5 Elina Svitolina.

That meant Fernandez came in having spent more than 12 1/2 hours on court through her six matches; Raducanu’s main-draw total was about 7 1/2 hours.

That seemed to be a factor, particularly over the second half of the 1-hour, 51-minute final.

From 4-all in the opening set, Raducanu took eight of the last 11 games. When she broke to take that set with a well-paced, well-placed forehand winner down the line, she stared at her entourage, then whipped her arms — and the fans reacted.

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 an unknown.

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

How quickly everything has changed.

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