Canadian teenager Eugenie Bouchard recovered from the loss of the first set to beat Ana Ivanovic and set up a semi-final date with fourth-seed Li Na at the Australian Open.
The 19-year-old, who was named the 2013 WTA newcomer of the year, held her nerve to record a hugely impressive in a 5-7 7-5 6-2 victory.
Ivanovic had gone into the game on the back of tough wins over Sam Stosur and Serena Williams - and the Serb needed lengthy injury time-out in the second set.
Bouchard, though, took full advantage to reach her maiden grand slam semi-final.
"I tried for sure to show I was calm," she said. "I did feel confident. Having lost the first set, I just tried to focus on what I had to do during the point to try to win, really just try to keep pressing her and moving forward.
"That's what kept me really calm. I felt like my game got a bit better as the match went on. In the first set I was close but I was missing shots just by a little bit.
"I think the matches I had last year on the big courts, like Maria Sharapova at the French Open, Ivanovic at Wimbledon, just being on those big stages gave me a lot of experience.
"Now walking out on centre court in Australia, I feel like I've been here before. I've been able to perform on big stages as well. It gives me that extra confidence."
Li remained on course for a third Australian Open final appearance with a 6-2 6-2 win over Italian Flavia Pennetta.
The 31-year-old, who lost to Victoria Azarenka 12 months ago, needed just an hour and seven minutes to complete a one-sided victory.
Li, who saved a match point against Lucie Safarova in the third round, said: "I think everyone wants to win a Grand Slam. But first you have to be in the semis, right?
"But I was really happy today. At least tomorrow I have a day off. I can talk with my coach Carlos Rodriguez and the team and prepare for the next round."
Our man at Melbourne Park, Tim Clement, looks at the remarkable rise of Eugenie Bouchard.
Bouchard was one of Sky Sports picks ahead of this year's Australian Open.