NEW YORK — Agnieszka Radwanska and Li Na reached the US Open third round Wednesday as defending men's champion Andy Murray impatiently waited to start his New York campaign since rain and lightning halted play. Radwanska, promoted to third seed after the injury-forced withdrawal of Maria Sharapova, defeated Spanish world No. 103 Maria-Teresa Torro-Flor, 6-0, 7-5 while Li, the Chinese fifth seed, beat 100th-ranked Swede Sofia Arvidsson 6-2, 6-2. Radwanska, who has never got beyond the fourth round in New York, was on course for a quick-fire win over Torro-Flor, her second successive Spanish opponent, when she raced through the first set in just 21 minutes, losing just seven points. But Torro-Flor, dressed in matching colours of blue and pink, made the Pole work for her win in the second set with three breaks of serve. Li, playing in her 30th Grand Slam and a New York quarterfinalist in 2009, will next face either British 30th seed Laura Robson, who knocked her out of the tournament in 2012, or France's Caroline Garcia. On Tuesday, top-ranked Novak Djokovic and 17-time Grand Slam champion Roger Federer advanced with ease but 2011 winner Samantha Stosur was ousted by US teen qualifier Victoria Duval. Six-time Grand Slam champion Djokovic who captured his fourth Australian Open crown in January, launched his quest for a fourth consecutive US Open final by beating Lithuanian 112th-ranked Ricardas Berankis 6-1, 6-2, 6-2. “I managed to make a lot of breaks in the beginning of the match and take over control,” Djokovic said. Djokovic fired 10 aces and 28 winners and needed only 82 minutes to put himself into a last-64 matchup against Germany's Benjamin Becker. Djokovic, the 2011 US Open winner who lost to Andy Murray in last year's final and last month's Wimbledon final, improved to 12-1 in Arthur Ashe Stadium night matches, what he called “the most special night matches of any tournament anywhere in the world.” Duval, a daughter of Haitian parents ranked 296th in the world, pulled the day's shocker with a 5-7, 6-4, 6-4 victory over Australian 11th seed Stosur in a tense struggle that lasted for two hours and 39 minutes. Duval jumped up and down with arms aloft after pounding a forehand winner to convert her fourth match point. Federer made a solid start to his bid for a sixth US Open title by defeating Slovenia's Grega Zemlja 6-3, 6-2, 7-5 in a match delayed a day by rain. “There wasn't much rhythm out there, but I was happy the way I played,” said Federer. “Overall I'm pleased to be in the next round.” The 32-year-old Swiss star, who as the seventh seed is at his lowest spot in the US Open since 2002, will face Argentina's Carlos Berlocq in round two. Federer, whose 56th Grand Slam start in a row matched South African Wayne Ferreira for the all-time record run, has only one title in his past 14 Slam starts, that coming last year at Wimbledon. After a second-round exit this year at Wimbledon, Federer took only 93 minutes to eliminate Zemlja despite surrendering a third-set break. Two-time Australian Open winner Victoria Azarenka, who lost to Serena Williams in last year's final, downed German Dinah Pfizenmaier 6-0, 6-0. The second seed from Belarus faces Canada's Aleksandra Wozniak next. Other seeded women joining Stosur on the way out were No. 17 Dominika Cibulkova, No. 20 Nadia Petrova and No. 31 Klara Zakopalova. Among men, No. 14 Jerzy Janowicz of Poland, a semifinalist at Wimbledon last month, was the most surprising to go, although he was treated by a trainer for a painful back during a 6-4, 6-4, 6-2 loss to 247th-ranked qualifier Maximo Gonzalez of Argentina. No. 15 Nicolas Almagro, No. 25 Grigor Dimitrov and No. 28 Juan Monaco also lost. — Agencies