Spectators wait out a rain delay on Court 7 during the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. Li Na, of China, returns a shot against Sofia Arvidsson, of Sweden, during the second round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. China's Li Na reacts to an instant replay of a shot against Sofia Arvidsson, of Sweden, during the second round of the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. Agnieszka Radwanska, of Poland, greets Maria-Teresa Torro-Flor, of Spain, at the net after winning their second-round match at the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. AP Photo/Kathy Kmonicek Poland's Agnieszka Radwanska reacts during a second round match against Maria-Teresa Torro-Flor, of Spain, at the 2013 U.S. Open tennis tournament, Wednesday, Aug. 28, 2013, in New York. NEW YORK (AP) - Thanks to the rain and the schedule makers, Serena Williams got an unexpected day off Wednesday at the U.S. Open. On a gray, drippy day at Flushing Meadows, tournament officials postponed the defending champion's second-round match against Galina Voskoboeva, along with seven others on the women's singles slate. Among those who did finish before the rain began were No. 3 seed Agnieszka Radwanska and No. 5 seed Li Na, both straight-set winners in matches that kicked off the Day 3 schedule. "It's tough for them," Li said after her 6-2, 6-2 victory over Sweden's Sofia Arvidsson, referring to all those whose schedules were thrown into turmoil. For me, just relax all day and do whatever I want. Among those who returned to the court after a pair of rain delays that ate up about four hours were Venus Williams and No. 6 seed Juan Martin del Potro. Tournament officials kept the night session in Arthur Ashe Stadium on the slate, meaning defending champion Andy Murray and American Sloane Stephens were still supposed to play. But officials postponed all second-round women's matches that hadn't started before the rain came, except one between Jamie Hampton and Kristina Mladenovic. They wanted to keep the winner of that match on the same schedule as the winner between Stephens and Urszula Radwanska. Besides Serena Williams, No. 8 Angelique Kerber, No. 9 Jelena Jankovic and No. 25 Kaia Kanepi got an extra day of rest. In her match, Radwanska dropped only seven points during a 21-minute first set, but the second lasted 66 minutes. Long, but not too long. "Played first match and then I'm done," Radwanska said. I can just relax, watch others and do treatment and do whatever I want. Sometimes it's good to play first, even when I have to wake up really early. Other early winners were 32nd-seeded Anastasia Pavlyuchenkova and, on the men's side, one-time top-10 player Marcos Baghdatis. 17 Kevin Anderson returned to the court after the rain delay and wrapped up a 7-5, 4-6, 6-2, 6-3 victory over Daniel Brands. With the storm bearing down in the early afternoon, video monitors around the Billie Jean King Tennis Center warned fans to seek shelter and avoid trees because of potential lightning, though thousands of ticketholders were milling about without much concern for severe weather. They're used to this scene. The U.S. Open has wrapped up a day late for five straight years because of rain delays. This year, the U.S. Tennis Association announced it was building a roof over Arthur Ashe Stadium as part of a renovation project that will cost $550 million. The roof could be ready by 2016, or 2017 at the latest. Even that wouldn't have alleviated a first-week logjam the likes of which the tournament faced Wednesday, with a full slate of matches in singles along with men's, women's and mixed doubles. In all, there were seven men's doubles, two mixed doubles and 11 women's doubles matched postponed, including one involving formerly retired five-time major winner Martina Hingis, who is teaming with Daniela Hantuchova. By the time the USTA had announced its revised schedule, Li's match was long over. "I'm happy," she said. Because at least I'm done with my job for the day.