Russia's Ekaterina Makarova reached the first grand slam singles semi-final of her career with victory over two-time US Open runner-up Victoria Azarenka.
Makarova, who is also through to the semi-finals of the women's doubles with Elena Vesnina, was the more consistent player throughout and won 6-4 6-2 to finally emerge triumphant in her fifth slam quarter-final.
Azarenka lost to Serena Williams in the final for the past two years and will drop out of the top 20 as a result of this loss.
The former world number one had played by far her best tournament since returning from a persistent foot injury at Eastbourne in June.
But it had not been an easy journey and she was pushed all the way by 21-year-old qualifier Aleksandra Krunic in the previous round.
Makarova, on the other hand, went into the match having not dropped a set and upset seventh seed Eugenie Bouchard last time out.
It was a contest of fierce hitting but it was left-hander Makarova who recovered from a break down to edge the first set with a break of serve in the final game.
The Russian is the leading female player to be coached by a woman having worked with Evgenia Manyukova since 2007.
Azarenka put the pressure on early in the second set but Makarova resisted and then broke for 4-2, prompting Azarenka to destroy her racquet.
It did not help her cause, though, with Makarova ending the match on a run of four games in a row, clinching victory when Azarenka placed a forehand wide.
Makarova said: "Finally I am in the semi-finals. I had five chances and finally I'm here. It's a great feeling."
The 26-year-old is the only left-hander to beat Serena Williams at a slam and she could meet the world number one in the last four.
On being coached by Manyukova, Makarova said: "I just really enjoy to work with her. Eight years we are working together and it's getting better and better."
Azarenka's press representative revealed after the match that the Belarusian had been unable to practise on Tuesday because of food poisoning.
Azarenka said: "I don't really want to talk about it. I just want to give credit to my opponent. She played really well today. Am I disappointed? Yes, I'm disappointed.
"But I feel like I tried my best with whatever I had. I just want to wish her good luck. That's it. I'm out of the tournament."
Azarenka could nevertheless take encouragement from the fact she reached the quarter-finals against most people's expectations given her struggles this season.
She said: "It's not the end of the world. I can take positives from this tournament. Two months ago I didn't even think that I was going to be able to play today.
"It's the first time since the Australian Open where I was able to play five matches during the tournament. Whatever I have done on and off the court during practice, I never give up on every single day.
"I have been working really hard. I know that's going to pay off. So today is just one of the days that I have to go through, and I'm going to go through it."
Meanwhile, the evergreen Kimiko Date-Krumm, who turns 44 later this month, achieved a career first by reaching the semi-finals of the women's doubles with Czech partner Barbora Zahlavova Strycova.
Date-Krumm's previous best run in doubles at a grand slam came in 1992, when she was a quarter-finalist in Australia.