US Open, Flushing Meadows
Dates: 30 August - 12 September Start time: 1600 BST
Coverage: Live text commentary on BBC Sport website and mobiles; updates on BBC Radio 5 live; live on Sky Sports
Wozniacki will become the world number one if she wins the tournament
Caroline Wozniacki remains on track for a first Grand Slam title after overcoming both Dominika Cibulkova and the windy conditions at the US Open.
The Dane, last year's runner-up, dominated the quarter-final to win 6-2 7-5 on an extremely blustery night at Flushing Meadows.
"It felt like playing in a hurricane," Wozniacki said afterwards.
She goes on to face Vera Zvonareva after the Russian earlier beat Estonia's Kaia Kanepi 6-3 7-5.
Wozniacki extended her winning streak to 13 matches with the victory, which was hard work in conditions that meant keeping the ball in play was an achievement.
The Dane made only 18 unforced errors, while Cibulkova conceded 43, and the 5ft 3in Slovakian struggled particularly in the early stages as she dropped serve three times in the first set.
In these conditions the most important thing is to find the right balance between being aggressive and being patient
She coped much better in the second set but could not force the tie-break that her play had merited, and Wozniacki secured a return to the semi-finals.
"When we were practising I thought 'Oh, it's not that windy today' but when we came out here I knew it was about just surviving, getting as many balls back in the court as possible and just run," she said.
And on facing Zvonareva in the semi-finals, Wozniacki added: "She's on a winning streak, playing really well, really aggressively, so it's going to be a really tough match.
"She made the finals of Wimbledon and is now in the semi-finals here so she's a great player and I'm going to go out there and do my best."
Zvonareva coped much better than Kanepi with the wind in the day's first quarter-final to reach the last four of the US Open for the first time.
Kanepi, the 31st seed, served six double-faults in the first set and was broken three times, and the errors kept coming in the second set, allowing seventh seed Zvonareva to break her four more times.
The match featured 88 unforced errors, 60 of them from Kanepi, and 11 breaks of serve as the Estonian in particular struggled to deal with the wind which swirls around Arthur Ashe Stadium at Flushing Meadows.
The players exchanged breaks in the first two games of the match before the 26-year-old Zvonareva gained the upper hand with another break in the fifth game and saw out the set.
Zvonareva was still unable to fully take command of the match however, the second set starting with four consecutive breaks of serve before the Wimbledon finalist was pegged back after taking a 4-2 lead.
But a touch of class from Zvonareva eventually helped her close out the match, a superb lob taking her to within two points of victory and two backhand errors from Kanepi sealing the 25-year-old's fate.
"It was very tough out there for both of us," said the Russian.
"We tried to show our best and sometimes we had some ridiculous rallies but I was putting all the effort into trying to hang in there no matter what the conditions and I'm really happy the way I pulled it out.
"In these conditions the most important thing is to find the right balance between being aggressive and being patient, between keeping the ball in play and going for your shots. I think I was able to find that balance."