She finished what might have been the most unprecedented – and unexpected – championship run in Grand Slam history with a flourish, a 108 mph ace.

Of course she did.

After 18-year-old Emma Raducanu defeated 19-year-old Leylah Fernandez 6-4, 6-3 in the US Open final Saturday, she dropped her racquet and fell to the court at Arthur Ashe Stadium. Hands over her face, she sobbed, trying to fathom what had just been achieved.

It’s a lot to take in. Raducanu became:

--The first qualifier in the history of the Open Era to win a major title.

--The first woman to win a major title in her second Grand Slam event. By comparison, Chris Evert and Venus Williams both got to the final in their third major – but lost.

--The youngest Grand Slam singles champion since 17-year-old Maria Sharapova won Wimbledon in 2004.

“I knew that I’d have to dig deep,” Raducanu said in her on-court interview. “We got through it, I think just staying in the moment, focusing on what I had to do and my process and the mindset really helped in those tough times.”

How improbable was this victory? Raducanu was ranked No.150 among WTA players coming in; going out, she’ll be an astonishing No.23, supplanting Johanna Konta, who was the top-ranked woman in Great Britain for 310 consecutive weeks.

For context, consider this: Raducanu has yet to win a main draw match on the WTA Tour. Let that soak in. Not one. She received wildcards into the main draw at Nottingham and San Jose, but lost her first-round matches.

Radacanu reached the fourth round at Wimbledon, amid a media frenzy but had to retire when she had difficulty breathing. In just over two months, she mastered her nerves – and navigated a brutally difficult path by winning three qualifying matches and seven in the main draw. Her opponents included Shelby Rogers – who had just upset No.1 Ashleigh Barty – Olympic gold medalist Belinda Bencic and talented Maria Sakkari in the semifinals.

Before Wimbledon, could she have imagined herself a Grand Slam singles champion?

“No, I wouldn’t have believed it at all, because at the beginning of the grass courts, I was coming fresh off my exams,” Raducanu said. “I had three weeks to practice before my first tournament. I thought Wimbledon was such an incredible experience. Fourth round, second week, I couldn’t believe it. I thought, what a great achievement."

Read more: How Leylah Fernandez won the hearts of New York during US Open fortnight

That’s 10 match-wins in less than three weeks and a perfect 20-for-20 in sets. The last woman to win the title without dropping a set in New York? Serena Williams in 2014.

In the end, Fernandez looked weary. In fact, she had played four consecutive matches that went three sets. The cumulative weight of taking down three Top 5 players – No.2 Aryna Sabalenka, No.3 Naomi Osaka and No.5 Elina Svitolina had to have been a factor. Her serve was not sharp; Raducanu forced 18 break points and converted four of them.

This was cracking good stuff, a throwback to the days of Martina Hingis and Justine Henin, with both players determined to stay anchored to the baseline, displaying terrific footwork and taking the ball early with exquisite timing. There was variety, texture – and toughness.

Raducanu was serving for the match at 5-3 when she fell and bloodied her knee and a medical timeout was called to bandage the wound. Ultimately, five minutes elapsed and Raducanu came back to convert her third match point.

“I also want to say that I hope to be back here in the finals,” Fernandez said during the trophy ceremony, “and this time with the trophy – the right one.”

Photo by Getty Images

She was laughing, but she wasn’t kidding.

Another measure of Raducanu’s ruthless efficiency:

For the tournament, she had 153 winners and only 113 unforced errors, while Fernandez was 200/200.

This was the first time two teenagers played for a major final since 1999, when 17-year-old Serena defeated 18-year-old Martina Hingis at the US Open.

This one felt like a similar turning of the page.

A decade ago at Wimbledon, Petra Kvitova was the first player born in the 1990s to win a Grand Slam singles title. Now we have our first champion born in the 21st century. Tennis, once dominated by England and colonial outposts in North American and Australia, has never been more globalized. Raducanu is a British citizen, born in Canada and with parents from China and Romania. Fernandez, a Canadian citizen, lives in the United States and her parents are from the Philippines and Ecuador.

We can’t possibly know how their careers will play out. Still it’s worth noting that their teenage predecessors turned out all right. Previously, the Open Era saw eight all-teenage Grand Slam finals. The winners, in chronological order: Stefanie Graf (twice), Arantxa Sanchez Vicario, Monica Seles, Iva Majoli, Hingis (twice) and Serena. Together, they would go on to win 64 major singles titles. Majoli, who beat 16-year-old Hingis in the 1997 French Open final, was the only one not to win another major.

"I’m very happy with myself, with the way I competed, and the play I played, the way I acted on court the past two weeks," Fernandez said. "I’ve improved a lot not only tennis-wise but emotionally and mentally.”

Nearing the end of the 2021 season, it’s clear women’s tennis has hit the refresh button. While Novak Djokovic is closing in on the calendar-year Grand Slam, there were four different women’s major champions – Naomi Osaka, Barbora Krejcikova, Ashleigh Barty and Raducanu, with Belinda Bencic winning gold in Tokyo.

Moreover, there are no fewer than nine players of consequence aged 22 or younger. Coco Gauff, at the age of 17, is already inside the Top 20. Raducanu and Fernandez aren’t far away.

Iga Swiatek, who won the 2019 French Open at 19, is 20, as is Amanda Anisimova, a semifinalist in Paris that same year. Bianca Andreescu, won the 2019 US Open at 19 and is now 21.

Marketa Vondrousova, who lost to Barty in the 2019 Roland Garros final and won silver in Tokyo, is 21. So is 2020 Australian Open champion Sofia Kenin and top-20 player Elena Rybakina.

“After the match, I just showered, same routines as always. I have no idea what I’m doing tomorrow," Raducanu said. "I’m just really trying to embrace the moment, really take it all in. I definitely think it’s the time to just switch off from any future thoughts or any plans, any schedule.

“I've got absolutely no clue. Right now, no care in the world, I'm just loving life.”