Before they stepped on court, there was nothing to suggest Andy Murray would have any trouble against Adrian Mannarino in the US Open’s second round. Murray, after all, is seeded No 3, owns two major championships including at Flushing Meadows in 2012, and had reached at least the quarter-finals at the last 18 grand slam tournaments he’d entered. Mannarino, meanwhile, is ranked 35th, has never won a tour-level title, and only three times in his career has even managed to win more than one match at a major. I just had to kind of tell myself that I would get there eventually. I had time to get back into it Andy Murray So it certainly came as a surprise when, in Thursday’s opening game, Mannarino broke Murray. About an hour later, Mannarino grabbed the opening set. And 45 minutes after that, the Frenchman took the second set, too. “I just had to kind of tell myself that I would get there eventually,” Murray said. “I had time to get back into it.” Despite a stuffy nose and scratchy throat, and generally looking as if he might be ready to wilt on another steamy day at Flushing Meadows – two more mid-match retirements, including by 28th-seeded Jack Sock of the United States, raised the total to 12 in the men’s draw so far – Murray put together his eighth career comeback from a two-set deficit and beat Mannarino 5-7, 4-6, 6-1, 6-3, 6-1. “He was looking for his rhythm,” Mannarino said, “and then I think that finally he found it.” Roger Federer had his rhythm from the start, compiling a 46-8 edge in winners while beating Steve Darcis of Belgium 6-1, 6-2, 6-1 at night. Former world No 1 Lleyton Hewitt made a dramatic farewell to the US Open, battling from two sets down and having two match points before losing to fellow Australian Bernard Tomic. In his final match at the grand slam event where he won his first major title in 2001, Hewitt fell 6-3, 6-2, 3-6, 5-7, 7-5 after three hours and 27 minutes. Hewitt has announced his retirement after January’s US Open and spent this year making his final grand slam stops, including Wimbledon, the site of his only other slam singles title in 2002. Against Murray, Mannarino, a lefty, delivered 12 of the match’s first 14 forehand winners and repeatedly found success with drop shots. But his play eventually dipped, while Murray really cleaned up his own act after the rough start: He went from making 21 unforced errors in the first two sets to only 14 the rest of the way. “He has such an unorthodox game, I didn’t really feel that comfortable at many points,” Murray said. “But I was happy, very happy, with the way I fought through that, finished the match stronger than him.” Sock took the opening two sets against 107th-ranked Ruben Bemelmans of Belgium and was three games away from winning in the third, but his body seized up because of cramps, unable to deal with the heat that topped 32 degrees Celsius. In a scary scene early in the fourth set, less than two hours in, Sock froze in place, his legs locked. A trainer helped the 22-year-old American sit down near the baseline, and Sock appeared to have trouble even extending his arm when Bemelmans walked around the net and leaned over for a handshake. “I didn’t have too much difficulty,” said Bemelmans, who will face French Open champion Stan Wawrinka next. Sock didn’t hold a news conference, instead releasing a statement that called his retirement “extremely disappointing”. There are only two American men remaining of the 16 who were in the draw: No 13 John Isner and unseeded Donald Young. “It’s tough to see,” Isner said about Sock’s cramping. “It’s not a fitness thing. I think that’s a big, big misconception. He’s in very good shape. He can play 50-ball rallies if he wants to. But he sweats a lot. His body was at a deficit of whatever it is – sodium, magnesium, potassium.” Denis Istomin of Uzbekistan stopped playing against 20th-seeded Dominic Thiem of Austria, citing an injured right leg. Including two retirements by women, 14 players have stopped playing during matches because of injury or illness, tying the 2011 US Open for the most through the first two rounds at a grand slam tournament. “Maybe it’s the end of the year – players are not as fit as in the beginning of the year,” Bemelmans said. “It’s the humidity, the heat – it’s all these combinations.” Fourth seed Caroline Wozniacki became the highest seed to fall in the upset-filled women’s draw when Czech Petra Cetkovska stunned the Dane 6-4, 5-7, 7-6 (7-1). The upset left only three of the top 10 women's seeds still alive in the year’s final grand slam number one Serena Williams, who is seeking the fourth women’s calendar-year grand slam, second seed Simona Halep and fifth seed Petra Kvitova.