Venue: Flushing Meadows, New York Date: 31 August - 13 September
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Wozniacki is into the semi-finals of a Grand Slam for the first time
Ninth seed Caroline Wozniacki brought an end to the amazing run of American teenager Melanie Oudin with victory in the quarter-finals of the US Open.
The Dane, 19, showed why she is ranked ninth in the world with a 6-2 6-2 win over the 17-year-old Oudin.
Wozniacki will next meet unseeded Belgian teenager Yanina Wickmayer in a first Grand Slam semi for both women.
Wickmayer beat Kateryna Bondarenko 7-5 6-4 in a scrappy encounter to win the first of Wednesday's quarter-finals.
Oudin, ranked 70, had become the story of the US Open as she beat Elena Dementieva, Maria Sharapova and Nadia Petrova on her way through to the last eight.
But after the day session had overrun, Oudin and Wozniacki began their match in a nearly empty Arthur Ashe Stadium as the night-session crowd filed in.
This has been a great experience for me, I've had a great run
It was a low-key atmosphere compared to Oudin's previous matches and her performance fell flat in the face of some measured play from Wozniacki.
The Dane broke straight away as Oudin made numerous unforced errors and again to lead 5-1, before Oudin finally got going on her forehand side and cut the deficit.
A nervous game followed from both players but Wozniacki converted her third set point when Oudin sent a forehand long.
The American's chance to get back into the match came at 2-2 in the second set but a wayward backhand and forehand saw two break points go begging and Wozniacki reeled off four straight games to seal a place in the last eight.
"She's such a strong player, she doesn't give you anything for free," said Oudin, who made 43 unforced errors.
"This has been a great experience for me, I've had a great run. Caroline played a great match today. I hope to come back next year and do even better."
Wozniacki said: "I've never passed the fourth round before. When I made the quarter-finals I was so happy. Now I'm in the semi-finals and hopefully I can try and win the next match."
Wickmayer, ranked two places above Bondarenko at 50th in the world, snatched a tight first set in the earlier quarter-final and, although Bondarenko led 4-1 in the second set, a series of errors cost her dear.
"Playing semis in a Grand Slam is great, amazing," said the 19-year-old. "Before this my best was second round, so it's so exciting, it's all been amazing.
"When you get to the third or fourth round you start surprising yourself but actually I've been staying pretty calm. I've worked really hard for this.
Wickmayer had won one match in six Grand Slams before New York
"Every match I can win. I'm really excited. I'm really happy."
Wickmayer becomes the second unseeded Belgian to reach the semi-finals at Flushing Meadows, following the progress of her idol, former world number one Kim Clijsters, on Tuesday.
Clijsters, who has come out of retirement to play in her first Grand Slam since the 2007 Australian Open, plays defending champion Serena Williams after beating Li Na in her quarter-final.
At 26, Clijsters is seven years older than Wickmayer, who had won only one senior match in six previous Grand Slams before this year's US Open.
Bondarenko was also in her first major quarter-final and made a slow start, struggling to compete with Wickmayer's attacking approach in the early stages of the match.
Wickmayer served for the first set at 5-4 before Bondarenko responded well to get her first break, but she was broken herself to love in the next match and the Belgian served out.
Her Ukrainian opponent improved at the start of the second set and seemed to have rediscovered the form that saw her thump Gisela Dulko 6-0 6-0 in the previous round as she moved 4-1 up, before Wickmayer won five games in a row to clinch victory.
"I missed a few opportunities," Wickmayer added. "I was pretty mad at myself. I kept fighting and kept hanging in there and just came back."
Bondarenko, 23, has still picked up enough ranking points this fortnight to catapult herself towards the top 30 and felt she did all she could to go further in the tournament.
"Even if I had a break point she didn't give me a chance to win it," said Bondarenko. "She just played unbelievable. When she was break point down she kept hitting winners."
In the girls' singles, Britain's Heather Watson beat America's Courtney Dolehide 6-3 6-2 in her second-round match.
Watson, seeded 11th, will play Annika Beck of Germany or Denmark's Mai Grage in the third round.
Laura Robson won through to the last 16 on Tuesday and plays Belgian 12th seed Tamaryn Bendler in her next match.