NEW YORK: Roger Federer revealed he struggled to breathe during his shock 3-6, 7-5, 7-6 (9/7), 7-6 (7/3) defeat to world number 55 John Millman at the US Open on Monday. The 37-year-old five-time champion labored to his earliest loss at the tournament in five years with his challenge sinking in the crushing humidity on Arthur Ashe Stadium. “I just thought it was very hot tonight. Was just one of those nights where I guess I felt I couldn’t get air. There was no circulation at all,” said 20-time major winner Federer who was bidding to clinch the US Open for the first time in a decade. “I just struggled in the conditions. It’s one of the first times it’s happened to me. “It’s uncomfortable. Clearly just kept on sweating more and more and more and more as the match goes on. You lose energy as it goes by. “But John was able to deal with it better. He maybe comes from one of the most humid places on earth, Brisbane!“ It was Federer’s first loss against a player outside the top 50 in 41 meetings at the US Open. “I felt a little bit guilty today because he didn’t have his best day today that’s for sure,” said Millman, a 29-year-old ranked 55th in the world. “I’m very aware he didn’t have a great day in the office. Probably to beat him I needed him to have an off day and I needed to have a good day.”