Out on the baseline of Court 10 at the Billie Jean King National Tennis Center, Emma Raducanu buried her face in her hands as if she couldn’t believe what had just happened.

She had beaten Zhang Shuai, the No.49-ranked player in the world, 6-2, 6-4 to advance to the third round of the US Open. And, so, Raducanu’s summer of suspended disbelief continues.

Raducanu, an 18-year-old from Great Britain ranked No.150, played her first WTA main-draw event in Nottingham. That was in early June, when she was ranked No.361.

Three months later, she’s contemplating Saturday’s third-round match with Sara Sorribes Tormo and a possible berth in the second week of a major. And, potentially, a crack at World No.1 Ashleigh Barty.

READ: Out of the spotlight, Raducanu engineers career surge in U.S. 

How on earth did this happen?

Like most overnight success stories, Raducanu has been a promising work in progress for years. She was born in Toronto to mother Renee, who is Chinese, and father Ian, a Romanian. They moved the family to Bromley, south of London, when Emma was 2 years old. Three years later, she played tennis for the first time.

US Open: Scores | Draws | Order of play

Coached now by Nigel Sears, the father-in-law of Andy Murray, Raducanu was granted a wildcard into Nottingham, won two of three matches and received another wildcard from the All England Club.

At Wimbledon, she was invited to practice with Garbiñe Muguruza, and it was a revelation.

“I was so chuffed just to be able to hit with her and see how intense she was,” Raducanu said. “It definitely made something click in my head. ‘Wow, this is the level I need to be training at. I need to be this intense if I want to achieve anything remotely near to what she has.’”

Raducanu was solid in a first-round victory over Vitalia Diatchenko and surprisingly poised in a second-round win over Marketa Vondrousova – less than one month from capturing the silver medal at the Tokyo Olympics. Sorana Cirstea was next, setting up a fourth-round match with Ajla Tomljanovic.

Raducanu was the youngest British woman to reach the fourth round at Wimbledon in the Open Era. The London sports pages and social media embraced the British teenager, causing a remarkable case of heightened hysteria for a tennis match. And while Raducanu was forced to retire during the second set with breathing difficulties, she had made a rare splash, reminiscent of Coco Gauff’s run to the fourth round two years earlier as a 15-year-old.

Another wildcard brought her to the Chicago 125, where she reached the final before heading to New York. With no wildcard available, Raducanu won three qualifying matches in three days – beating Bibiane Schoofs, Mariam Bolkvadze and Mayar Sherif.

In the main draw, Raducanu took out Stefanie Voegele in the opening round, then Zhang in the second. What to expect Saturday?

Not surprisingly, Raducanu and Sorribes Tormo, who is ranked No.41, have never played. The 24-year-old from Spain won her first WTA title this year, at Guadalajara. She was a quarterfinalist in Montreal and, most recently, a semifinalist in Cleveland.

Can Raducanu continue her breakthrough season at a tournament in which no Top 20 seed has yet to lose?

"I love it here,” she said after her last match. “I'm extremely grateful for all the support I've been receiving here in the States. Honestly, it's taken me a bit by surprise.”

The rest of Saturday’s matches from the top half of the draw:

No.1 Ashleigh Barty vs. Shelby Rogers

Barty, who has yet to reach the quarterfinals in New York, defeated 18-year-old Clara Tauson 6-1, 7-5.

Rogers, a quarterfinalist here last year, beat Cirstea 7-5, 6-2.

“Whether that’s a first round or a final, my preparation and everything doesn’t change,” Barty said in her post-match interview. “I think that’s been a massive part of our year is accepting that you don’t win every single tennis match and you’re certainly not entitled to make big finals or put yourself in the latter stages of tournament. You have to earn that right. I think chipping away in these first two matches has been good.

“The tennis hasn’t been as clean as it was a couple weeks ago, but we accept that. We keep working and go back to the practice court tomorrow, and now we give ourselves another opportunity in the third round to try and rectify that.”

Head-to-head: 5-0, Barty, who has beaten Rogers four times this year along – in a span of three months (Melbourne 500, Australian Open, Charleston and Madrid).

No.4 Karolina Pliskova vs. Ajla Tomljanovic

Pliskova outlasted Amanda Anisimova in a spectacular late-night match, 7-5, 6-7 (5), 7-6 (7), when one last backhand found the net. The match ran 2 hours, 23 minutes – and Pliskova hammered 24 aces.

Tomljanovic was a 7-6 (6), 6-4 winner over No.30 Petra Martic, ending a career-long drought.

Great escapes 2021: Winning from match point down

Head-to-head: 5-1, Pliskova has won the last five, including 2020 Brisbane.

No.6 Bianca Andreescu vs. Greet Minnen

Andreescu continued her unbeaten record at the US Open, defeating Lauren Davis 6-4, 6-4. The 21-year-old Canadian is now 8-0 in New York.

In an odd footnote: Andreescu has won her past 11 matches against Americans.

Andreescu’s facing an underdog of enormous proportions. The No.104-ranked Minnen defeated Liudmila Samsonova 6-4, 6-4. She’s the fifth lucky loser in the 50-plus years of the Open Era to reach the third round of the US Open.

Head-to-head: 0-0.

No.11 Belinda Bencic vs. No.23 Jessica Pegula

A rematch of their first-round match at the recent Tokyo Olympics, which Bencic won 6-3, 6-3 on her way to the gold medal.

To get here, Bencic – a US Open semifinalist two years ago – defeated Martina Trevisan 6-3, 6-1.

Pegula beat Misaki Doi for the fifth time in six matches, 6-3, 6-2.

This season has put the 27-year-old American over the top. Pegula’s record in majors is now 12-11 and 5-4 at the US Open. Her best major result came early this year when she reached the quarterfinals at the Australian Open. Her won-loss for the year is an impressive 31-16.

Head-to-head: 2-0, Bencic.

No.7 Iga Swiatek vs. No.28 Anett Kontaveit

It didn’t look good for the 2020 French Open champion when, already down a set, she entered a second-set tiebreaker against Fiona Ferro. Swiatek broke Ferro’s serve four of five times, then ran away in the third set 3-6, 7-6 (3), 6-0.

Kontaveit, a 6-4, 6-1 winner over Jil Teichmann, comes in with momentum. Last week, she won a title in Cleveland.

Head-to-head: 2-1, Kontaveit (Swiatek took the most recent meeting at 2021 Roland Garros.

No.10 Petra Kvitova vs. No.17 Maria Sakkari

This is the terrific kind of high-quality, third-round matchup the Grand Slams can produce. Kvitova handled Kristyna Pliskova 7-6 (4), 6-2. Sakkari was a 6-4, 6-2 winner over Katerina Siniakova.

Neither player has dropped a set here. Kvitova has never been beyond the quarterfinals at the US Open, while Sakkari has yet to advance past the fourth round.

Head-to-head: 3-2, Kvitova (The Czech broke a 2-all tie with a win this year at Stuttgart; the past four matches have all gone three sets).

No.14 Anastasia Pavlyuchenkova vs. Varvara Gracheva

An all-Russian confrontation.

Pavlyuchenkova defeated qualifier Anna Karolina Schmiedlova 6-2, 5-7, 6-2, while Gracheva upset No.24 seed Paul Badosa 6-4, 6-4.

Head-to-head: 1-0, Pavluchenkova in a Round of 16 win at 2019 Moscow.