- Serena Williams to face Caroline Wozniacki in U.S. Open semis
- Williams beats Russian 17th seed Anastasia Pavlyuchenkova 7-5 6-1 in quarters
- World number one Wozniacki defeats Andrea Petkovic 6-1 7-6
- Samantha Stosur to face unseeded Angelique Kerber in other semifinal
Serena Williams will face world number one Caroline Wozniacki for a place in the U.S Open final after both women recorded last eight victories in New York.
After two days of the tournament were lost due to rain, both women were out on court earlier than usual but wasted little time in booking their place in the final four.
Williams faced a tough first set against Russia's Anastasia Pavlyuchenkova before running out a 7-5 6-1 winner.
After overcoming an erratic start to the match she told reporters that two days of indoor practice may have affected her form.
"Maybe that had something to do with it," said Williams. "Indoors I think is a little faster."
The 13-time major champion will now face Wozniacki, who is yet to win a grand slam despite holding the world number one ranking for the majority of the past year.
Wozniacki, from Denmark, defeated Germany's Andrea Petkovic 6-1 7-6 on Court 13 after being moved from the Louis Armstrong Stadium which was still wet after two days of torrential rain.
She told Sky Sports: "I'm just happy to be through happy to be in the semifinals. Its a tough battle out here I'm happy to have closed it out in two.
"I know that Andrea's a fighter and she's not going to give, I tried to fight for every point.
"I'm feeling OK, when you're out there on court your adrenalin is pumping you just think about the yellow ball and playing it inside the lines."
Australia's Samantha Stosur, the ninth seed, also moved into the semifinals as she defeated last year's runner-up Vera Zvonareva 6-3 6-3.
Stosur will now play unseeded Angelique Kerber, from Germany, in the semifinal after she beat Italy's Flavia Pennetta 6-4 4-6 6-3.