This is a Tennis Podcast in two parts.First of all, David and Catherine recorded almost half an hour of chat about the day session, reflecting on wins for Naomi Osaka, Madison Keys and Novak Djokovic, and looking ahead to the quarter-finals.Then the night session happened. And all hell broke loose. At 2:15am, David and Simon Briggs tried to pick up the pieces following Roger Federer’s shock defeat to John Millman. Federer hit 76 unforced errors, made 10 double faults and landed less than 50% of his first serves. Why was he so off his game? Where does he go from here? In his press conference, Federer admitted that he suffered badly in the heat and humidity. Has he ever sweated so much?Also in the night session, Maria Sharapova endured her first ever defeat under the lights in New York against Carla Suarez Navarro. How much longer will Sharapova put up with not contending for Grand Slams?There will daily editions of The Tennis Podcast throughout the US Open fortnight. The Tennis Podcast is produced in association with the Telegraph and sponsored by Amazon Prime Video, the new home of the US Open in the UK.  See acast.com/privacy for privacy and opt-out information.