WUHAN, China - Johanna Konta pulled off the biggest upset of the Dongfeng Motor Wuhan Open on Wednesday night, battling back from the brink of defeat to stun the No.1 seed, Simona Halep.

It's been a breakthrough few months for Konta - after leaving the grass court season ranked outside the Top 100, she won a string of titles on the ITF Circuit and then, as a qualifier, made it all the way to the fourth round of the US Open. She came into Wuhan this week up at No.66 in the world.

She scored her first two Top 10 wins in that time, over Ekaterina Makarova and Garbi馿 Muguruza, and against the No.2-ranked Halep she looked like a world-beater too, racing through the first set, 6-3.

Halep struck back in a big way, winning seven of eight games from 4-3 ahead in the second set to take that second set, 6-3, and build a 5-1 lead in the third, seemingly on her way to a runaway victory.

But she never sealed the deal, and Konta - battle hardened through the qualifying rounds and two more victories in the main draw already - started ripping her huge groundstrokes into the corners again, reeling off the last six games in a row to finish off the improbable upset in style, 6-3, 3-6, 7-5.

Konta is the first British woman to beat a Top 2 player in almost 34 years - the last British woman to achieve the feat was Sue Barker, who beat a No.2-ranked Tracy Austin at Brighton in October 1981.

"It was two hours and 17 minutes of very, very tough tennis for me," Konta said in her on-court interview after the match. "Simona really played some unbelievable tennis in parts - she may not be feeling her best, but I'm just really happy I was able to take a few of the chances I created.

"I'm feeling humbled and blessed I get to come back tomorrow and compete again."

Awaiting Konta in the quarterfinals will be Venus Williams, who kept her own unlikely run - she's unseeded here - going with a 6-3, 6-4 victory over the tournament's No.7 seed, Carla Su醨ez Navarro.

Su醨ez Navarro had beaten Williams in three of five previous meetings, including Miami this year.

"We've had some great matches in the past, including a nice one earlier this year where she came out the victor - it was super close," Williams said of the Spaniard. "When I play her, I know that I have to be concentrated because she's just a great competitor. She's always played well against me, too.

"I had some luck because I think she missed a few shots today, and it gave me some openings."

Williams and Konta will be playing against each other for the very first time.