Caroline Wozniacki brought fellow teenager Melanie Oudin's giant-killing run at the US Open to an end under the lights at Arthur Ashe Stadium.
American 17-year-old Oudin, ranked 70th in the world, had grabbed all the headlines in the women's singles over the previous nine days as she upset a series of Russian seeds en route to the quarter-finals.
Yet having knocked out No.4 Elena Dementieva, former champion and 29th seed Maria Sharapova and 13th seed Nadia Petrova in come-from-behind three-setters, Oudin finally met her match as 19-year-old Danish ninth seed Wozniacki, also playing her first grand slam quarter-final, defeated her in straight sets 6-2 6-2.
Wozniacki's win sets up a semi-final clash with another unseeded teenager, world number 50 Yanina Wickmayer of Belgium, a 7-5 6-4 winner over Kateryna Bondarenko of the Ukraine.
'It was a really tough match," Wozniacki said. 'Melanie had such a great run and she played an amazing tournament so I'm just going to enjoy this match.
'The next match I have nothing to lose. I mean, I'm in the semi-final of a grand slam.'
Oudin was also in a positive mood following her exit.
'I can take a lot from this,' Oudin said. 'I've had a great run here but Caroline had a great match today. I hope to come back next year and do even better."
The Belgian teenager, ranked 50th in the world, had not previously got past the second round of a grand slam event but she reached the last four with a straight sets win over Ukraine's Kateryna Bondarenko at Arthur Ashe Stadium.
The 19-year-old now becomes the second Belgian to reach this year's semi-finals, joining former world number one Kim Clijsters in the last four at Flushing Meadows.
Wickmayer defeated Bondarenko, ranked two places below her, 7-5 6-4, coming from 4-1 down in the second set to win her first grand slam quarter-final.
'It has surprised me in one way," Wickmayer said. "I have been felling really well the last few weeks.
'I've been playing a couple of great matches and I'm really playing with a lot of confidence.
'Coming here I was feeling pretty good and physically and mentally really strong ...but if it's the first great Grand Slam you've played, when you get to the third, fourth round you start surprising yourself.
'But actually, I've been staying pretty calm. I've worked really hard for this.'
Wild card Clijsters is set to play her semi-final against defending champion and second seed Serena Williams, the only player from the top eight left in the women's draw.
Both semis are scheduled for Friday.
