Greece's Maria Sakkari beat defending champion Iga Swiatek to reach her maiden Grand Slam semi-final at the French Open at Roland Garros.
She will face Czech Barbora Krejcikova, who won a nervy encounter with American teenager Coco Gauff 7-6 (8-6) 6-3.
Sakkari, the 17th seed, is now the highest-ranked woman in the draw after seeing off Swiatek 6-4 6-4.
"I am speechless, it is a dream come true," said the 25-year-old. "It is a very nice feeling."
Krejcikova, meanwhile, saved five set points from 17-year-old Gauff in the opener before the world number 33 went on to seal victory on her sixth match point.
"I never imagined I would be standing here one day," said Krejcikova.
"Already for me this is something I have never dreamed of. I was really playing a great match and Coco is incredible - she is 17, it's amazing."
It means all four semi-finalists in Paris are into the last four at a Grand Slam for the first time.
Russian 31st seed Anastasia Pavlyuchenkova will face Slovenia's world number 85 Tamara Zidansek in the opening semi-final on Thursday.
Sakkari takes 'huge step' into semis
Eighth seed Swiatek headed into her quarter-final meeting with Sakkari as the highest-ranked woman left in the draw, but her title defence was ended as she struggled with a thigh injury in the second set.
Sakkari had already taken a hard-fought opening set in which the pair exchanged early breaks.
It was the 25-year-old who then edged into the lead and held on to clinch set point with a punchy backhand winner, roaring to the 5,000 fans inside Court Philippe Chatrier.
After being broken early in the second, Swiatek had treatment on her right leg and needed a medical timeout, returning with her thigh heavily strapped.
The 20-year-old Pole remained competitive but was unable to overturn Sakkari's advantage as the Greek moved into the first Grand Slam semi-final of her career.
"I couldn't have done it without my team and their support," she said. "We still have a long way to go, but we made a huge step today."
Swiatek had won 22 sets in a row at Roland Garros but saw that record ended by Sakkari, who played smartly as she unpicked the Pole's usually reliable forehand.
Afterwards, Swiatek said her injury was "nothing serious" but added she had been "stressed" in the build-up and had only slept for "a few hours".
"I didn't play my best tennis that's for sure," said the 2018 junior Wimbledon champion.
"Maria did a good job with playing at my forehand, which wasn't working pretty well. It's good for her that she saw that. She picked good tactics.
"I think the past couple of weeks hit me yesterday. I just didn't have good days, I couldn't do physical recovery well because I was stressed.
"I didn't play well tactically and also technically. I was on my heels."
Krejcikova fights back as frustrated Gauff slips to defeat
Gauff made the perfect start to her first Grand Slam quarter-final, eventually seizing her fourth break point in Krejcikova's opening service game as she opened a 3-0 lead, only for Krejcikova to claw back the deficit - surviving another break point before holding to level at 3-3.
Gauff, junior champion in 2018, held firm under pressure on serve before breaking the Czech for a second time but her failure to take her first set point allowed Krejcikova back in.
The American responded admirably but Krejcikova rescued two more set points - one with a superb line shot - to set up a nervous tie-break.
Gauff battled back from 2-0 behind to set up further set points at 6-4 before a steely Krejcikova once again dug in to win four successive points and take the opening set.
Gauff then failed to convert a break point in the first game of the second set and her hopes unravelled as Krejcikova held serve and immediately earned a break of her own.
The 25-year-old, who knocked out fifth seed Elina Svitolina in the third round, moved 4-0 ahead as a frustrated Gauff double-faulted before smashing her racquet on the clay, with Krejcikova eventually closing out at the sixth time of asking in one hour and 50 minutes.
Krejcikova is a two-time Grand Slam doubles champion and on Tuesday also reached the semi-finals of the women's doubles alongside fellow Czech Katerina Siniakova.
"I never really wanted to be a doubles specialist. Everybody just put a label on me, 'you play doubles, you are a doubles specialist'," said Krejcikova, who won the 2018 French Open and Wimbledon titles with Siniakova.
"I want to play singles, I want to work hard, improve my game.
"It's very nice when I have a match point and I finish the point, I can raise up my hands and enjoy the moment. I feel that's where I want to be, that's where I always wanted to be."
'This one will be on my mind for a couple days'
Gauff put the defeat into perspective, saying: "I'm obviously disappointed that I wasn't able to close out the first set. To be honest, it's in the past, it already happened.
"After the match, Enzo, my hitting partner, told me this match will probably make me a champion in the future. I really do believe that.
"This one will be on my mind for a couple days, for sure. I think just reflecting on it, it's over, so I'm not going to say, 'Oh, if I did this, if I did that'.
"I think in the moment I did what I thought was the best decision and I have to stick on that."
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