Johanna Konta reached the US Open quarter-finals for the first time by edging an unpredictable match against Czech third seed Karolina Pliskova.
Konta, 28, fought back from a set and 3-1 down to win 6-7 (1-7) 6-3 7-5.
She will face Ukrainian fifth seed Elina Svitolina or American 10th seed Madison Keys in the last eight.
"I've been in the fourth round twice before so reaching the quarter-finals is a massive achievement for me," said the British number one.
"The key was to keep going, with Karolina you know there will be massive portions of the match where I don't feel effective.
"It is about staying out there and trusting the fundamental things. It was a great match and I'm so happy."
The 16th seed missed chances in the first set before composing herself to punish an out-of-sorts Pliskova at Flushing Meadows. The Czech won 77% of points on her first serve and served 16 aces but those statistics were undermined by nine double faults and a second serve which earned her just seven points.
Konta has been hitting clean groundstrokes all tournament and continued to trust her ability against the similarly powerful Pliskova, landing 45 winners which outnumbered her unforced errors and proved to be a key differential.
Konta, who is the first British woman to reach the quarter-finals in New York since Jo Durie in 1983, has now made the last eight at all four Grand Slams.
She reached the French Open semi-finals and Wimbledon quarter-finals earlier this year.
On emulating Durie, Konta said: "I'm really pleased with that and, more specifically, this season to make it three quarter-finals in successive Grand Slams is a tremendous achievement.
"I will enjoy this but I have to keep looking forward and try to go one, two or three steps further."
Konta shows mettle to win another decider
Konta, supported again by actor Tom Hiddleston in her player box, started strongly against an opponent who had won six of their seven previous tour-level meetings.
She broke to love in the first game and continued to create more opportunities as the tall Czech struggled to land first serves, enabling Konta to dismantle Pliskova's second serve on her way to setting up nine points for a double break in the opening set.
Pliskova rallied to save all of them and it looked likely to prove costly for Konta when her service game - which she had only dropped twice in her previous three matches - suddenly disintegrated.
Konta failed to land a first serve as she tried to see out the opener at 5-4, paying the price as the Czech rediscovered her biggest weapon to instead take the advantage.
Pliskova looked completely in control as she broke in the first game of the second set and won nine out of 10 points with Konta's game starting to become ragged.
But, after the pair traded two more successive breaks, momentum shifted back to Konta, who won five games in a row to take an engrossing match into a decider.
Konta had won 16 of her 19 three-set matches this year and looked set to improve that tally when a poor service game from Pliskova, which featured three unforced errors and a double fault, left the Briton serving for the match.
However, as when she served for the first set, nerves seemed to take hold and Pliskova threatened to level by bringing up break point. Konta, though, composed herself again with a brave forehand winner down the line.
After missing a first match point, she reset again to win at the second opportunity when 27-year-old Pliskova - still searching for a maiden Grand Slam title herself - hit long to go down in two hours and 20 minutes.
"It was important not to panic or be worried," Konta said about fighting back from a set and a break down.
"I was doing a lot of good things out there and I kept into perspective I was playing the number three player in the world.
"I was pleased with what I was doing in that first set, even though I wasn't able to come through, and I definitely felt there was a lot for me to build on.
"I trust in my ability to create more opportunities and I managed to do that."
'Konta seems to relish mixing it with the elite' - analysis
BBC tennis correspondent Russell Fuller at Flushing Meadows
Johanna Konta won that match the hard way. Many would have subsided after losing a first set they had dominated - especially after being broken twice in a row at the start of the second.
But Konta has an extraordinary third-set record this year, and seems to relish mixing it with the elite.
She has won her past four matches against top 10 players in Grand Slams - against Sloane Stephens twice, Petra Kvitova and now Karolina Pliskova.
The serve is the bedrock of her game, but she also hit bravely and freely from the baseline when the match was up for grabs.
To have reached the last eight of all four Grand Slams is a mighty achievement, and she is only the 14th active player to have done so.