Play finally got underway after a 90-minute rain delay at the US Open on Wednesday, bringing relief to organisers a day after torrential downpours wiped out the entire programme. All four women's quarter-finals, two men's quarter-finals and the remaining four men's fourth round matches were all due to be played. Action eventually started at 1230 with 10 singles matches to be played. In the men's last 16, which should have been completed on Tuesday, defending champion Rafael Nadal took on Gilles Muller and fourth seed Andy Murray was due to face America's Donald Young. Former winner Andy Roddick was playing David Ferrer while John Isner and Gilles Simon were also due on court. In women's last eight ties, top seed Caroline Wozniacki, still searching for a first Grand Slam title, takes on Germany's Andrea Petkovic while three-time winner Serena Williams was up against Anastasia Pavlyuchenkova. Second seed Vera Zvonareva was facing Australia's Samantha Stosur with unseeded German Angelique Kerber meeting Italy's Flavia Pennetta. Men's quarter-finals action saw world number one Novak Djokovic playing fellow Serb Janko Tipsarevic and five-time champion Roger Federer clashing with Jo-Wilfried Tsonga. Tuesday's wipeout was the first time both the day and night sessions had been cancelled at the tournament since 2006.