NEW YORK (AFP) – Teen upstarts Caroline Wozniacki of Denmark and Yanina Wickmayer of Belgium fought through the tension to reach their first Grand Slam semi-finals with nerve-testing US Open triumphs.
Ninth seed Wozniacki, until now the top-ranked woman never in a Slam final eight, ousted 70th-ranked US teen Melanie Oudin 6-2, 6-2 while Wickmayer, never before past a Slam second round, beat Ukraine's Kateryna Bondarenko 7-5, 6-4.
The 19-year-olds will meet in a Friday semi-final with the winner to play for a US Open title Saturday against either defending champion Serena Williams, an 11-time Grand Slam champion, or Belgian Kim Clijsters, back after a two-year layoff to start a family.
Wozniacki shrugged off the cheers at Arthur Ashe Stadium for home-nation hero Oudin and snuffed out her comeback bid early in the second set.
"I was really nervous out there. I'm so happy I fought so well and was able to pull the match out," Wozniacki said. "It was important to keep positive. I knew if I showed emotion she was going to pick up on it."
Oudin, 17, was the giant killer of Flushing meadows, ousting former world number one Maria Sharapova, fourth seed Elena Dementieva and 13th seed Nadia Petrova after dumping former world number one Jelena Jankovic at Wimbledon.
But after a 6-1 run in Grand Slam matches where she lost the first set, "Oudini" at last found a trap she could not escape.
"I was a little bit fragile but Caroline made me like that," Oudin said. "She made me frustrated I had to hit a winner on her. Before I would get some free points because girls went for more. Caroline was extremely consistent."
Wickmayer, ranked 50th, joined compatriot and idol Clijsters as the first pair of unseeded women in the last four at the same US Open.
"Playing the semis in a Grand Slam is great," Wickmayer said. "It's 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. Every match I can win. I'm really excited. I'm really happy."
Wozniacki became the first Danish man or woman to reach a Grand Slam semi-final, surpassing the 1978 Australian Open women's quarter-finals run by Dorte Ekner as her homeland's best showing.
By winning her 10th match in a row, Wozniacki is assured of rising to a career-high seventh in the rankings. She had been the youngest player in the top 20 and the highest in the rankings never to reach a Slam quarter-final.
Oudin, who made 43 unforced errors to just 20 for Wozniacki, surrendered a break to drop the first set.
The relentless Dane rescued two break points in the third game of the second set when Oudin swatted errant forehands and saved two more to hold in the fifth game, the American sending a backhand wide and a forehand beyond the baseline.
"I knew they were very important moments," Wozniacki said. "Maybe before I would break down, throw my racket. I told myself I have to not show any emotions because if I do that it will help Melanie."
Inspired Wozniacki never dropped another game, breaking Oudin in the sixth game when her forehand nicked the net cord and landed wide and again at the end when the American sent a backhand long to fall in 88 minutes.
Wickmayer, whose mother died of cancer at age nine and whose father gave up his construction job so his daughter could follow her tennis dream, won the last five games against Bondarenko to advance after one hour 41 minutes.
"I missed a few opportunities," Wickmayer said. "I was pretty mad at myself but I kept on fighting, kept hanging in there and I was able to come back."
Wickmayer was broken serving for the first set at 5-4 but broke back in the next game, held for the set and broke Bondarenko to open the second set. The Ukraine 23-year-old broke her twice for a 4-1 edge but never won another game.
"Even if I had a break point she didn't give me a chance to win it. She just played unbelievable. When she was break point down she kept hitting winners," Bondarenko said.
"I don't think I was too nervous but for sure I was nervous a little bit."