Britain's Johanna Konta staged a superb fightback to beat world number two Simona Halep 6-3 3-6 7-5 and reach the quarter-finals of the Wuhan Open.
After winning the first set, Konta looked set for defeat as her Romanian opponent won the second and was 5-1 up in the decisive third.
However Halep had no answer as Konta fought back to progress.
The 24-year-old will next play former world number one Venus Williams for a place in the last four.
Konta becomes the first British woman to beat a world number two since Sue Barker defeated Tracy Austin in 1981.
"It was a very tough match," said Konta.
"Halep played at an unbelievable level. I was really happy I was able to take a few of the chances I created."
|Who is Johanna Konta?|
|Born in Sydney, Australia, to Hungarian parents Gabor (hotelier) and Gabriella (dentist)||Konta became a UK citizen in May 2012, and has played 11 matches for the GB Fed Cup team since 2013|
|She speaks Hungarian and English, and was introduced to tennis aged eight by her parents||Her career-high world ranking of 66 is set to rise into the top 50|
Konta, who will replace Heather Watson as British number one, has won 21 of her past 22 matches this season.
She began the year ranked 150th but will pass her compatriot in next week's rankings. Watson is ranked 60th in the world.
Konta came through two rounds of qualifying in Wuhan, joining 19 of the world's top 20 in the main draw, and reached the last 16 after Victoria Azarenka retired with a leg injury.
Konta goes where few have gone before
While no British woman has beaten a world number two for 34 years, there have been some memorable scalps - and some near misses.
British number three Laura Robson defeated Kim Clijsters and Li Na at the 2012 US Open, while Watson came close to beating world number one Serena Williams at Wimbledon this summer.
This year, Konta has twice beaten Wimbledon finalist Garbine Muguruza.
Konta's year in numbers
- In 2011 she was world number 305, now she is ranked 66 and will climb further
- She has won $378,129 (£250,177)
- Konta has won 42 singles matches and lost 17 (71% win percentage)
- She has won two titles on the ITF Circuit
- Her only defeat in 22 matches came at the US Open, when she lost to Petra Kvitova in the last 16
'It's not an accident'
"Playing Venus is a childhood dream," said Konta.
"I feel lucky and humble I get to play so many matches, and be able to win a few of them. There's a lot of hard work behind it. It's not an accident or a click.
"Everything is a process and a journey, and it's nice to be on a high right now.
"I'm not that amazed, overwhelmed or unnecessarily excited about every match. I'm an ambitious person and believe in my own ability.
"But I know how tennis works - there are ups and downs."
What they say
Great Britain's Fed Cup coach Judy Murray on BBC Radio 5 live:
"She's put in hard work on the mental side. She has worked at managing her emotions in tight situations. Who would have believed she would transform her game so much in the last nine months? Huge credit to her.
"She can take another big scalp on Thursday. The way she's playing, I wouldn't put anything past her. She's a dangerous opponent for anybody right now."
Former British number one Annabel Croft on BBC Radio 5 live:
"She's been on a meteoric rise since the grass-court season started at Eastbourne. She's a transformed player from the one we saw a year ago. Today was the biggest win of her career by a long way.
"She's a grafter, a lovely girl and appreciative of everything handed out.
"You couldn't wish the success on a nicer person. It proves hard work, graft and application to the task has paid off.
"She has a huge serve and used to have a vulnerable forehand, but that has disappeared. The backhand is a world-class shot. She is also extremely fit. That combination, alongside having a sports psychologist, means she is becoming a formidable opponent for anybody."
Venus marches on
Seven-time Grand Slam champion Williams had little trouble reaching the last eight as the American beat Spain's Carla Suarez Navarro 6-3 6-4.
The 35-year-old, who claimed her 700th career victory in the previous round, saw off Navarro in one hour and 29 minutes.