|Venue: Flushing Meadows, New York, Dates: 31 August-13 September|
|Coverage: Live radio and text commentary on every Andy Murray match plus selected others.|
Second seed Roger Federer raced past Argentina's Leonardo Mayer in 77 minutes to reach the second round of the US Open at Flushing Meadows.
The five-time champion won 6-1 6-2 6-2 on a hot afternoon in New York.
Fifth seed Stan Wawrinka beat Albert Ramos-Vinolas 7-5 6-4 7-6 (8-6), while Andy Murray and Petra Kvitova progressed in the night session.
Women's second seed Simona Halep progressed when Marina Erakovic could not continue at 6-2 3-0 down.
The New Zealander was the latest in an unusually high number of retirements over the first two days.
Lucie Safarova was another leading woman to make an early exit, the sixth seed and French Open runner-up losing 6-4 6-1 to Ukraine's Lesia Tsurenko.
Fifth seed Kvitova swept past German qualifier Laura Siegmund 6-1 6-1 to complete the first round, after Murray had earlier beaten Nick Kyrgios 7-5 6-3 4-6 6-1.
Heat & humidity takes its toll
After seven withdrawals on Monday - the highest number at a Grand Slam for nine years - Erakovic, Thanasi Kokkinakis, Ernests Gulbis and Aleksandr Nedovyesov took the tally to 11 on Tuesday.
Not all of the retirements were directly related to conditions at Flushing Meadows, but temperatures in the mid-30s and punishing humidity took their toll.
Kokkinakis battled through to the fifth set against Richard Gasquet despite being barely able to move and forced to serve under arm.
"I didn't feel tired physically, which is the most frustrating thing about it," said the 19-year-old Australian, who lost 4-6 6-1 4-6 6-3 2-0 after almost three hours on court.
"I actually felt all right. My energy levels were good, and then I went up to hit a swing and volley or something, and both my calves - it was just disaster. Yeah, I'm pretty shattered."
Federer enjoys calm on Ashe
Federer is playing at Flushing Meadows for the 16th time, so is the perfect person to evaluate the effect of the new roof structure emerging across Arthur Ashe Stadium.
"It has changed. Forever," said the 34-year-old, bidding to become the oldest US Open champion in 45 years. "I think it's going to increase the level of play from all players. If you don't have to fight the wind you can play closer to the lines and make it better tennis.
"So probably it might be better for the top guys, my opinion."
Wozniacki turns the tables
John Isner faced an unexpected inquisitor when going through his obligatory post-match news conference. A familiar voice from the unfamiliar location of the media seats quizzed the American about his poor timing off court.
"Just because you have been playing really well leading up to the US Open, and you're close to the top 10 again, doesn't mean that you should push my press conference out," said Caroline Wozniacki. "I would appreciate you being on time."
Isner, who defeated Malek Jaziri 6-2 6-3 6-4, responded: "Now that I'm close to the top 10, Caroline is actually talking to me again.
"When I was ranked like 90 she would walk right by me. If I could get in single digits I think I can get some of Caroline's attention. That's my goal."
Quotes of the day
"I haven't done it in 17 years, so why start now? At the same time, you might think, who cares, you know?" Roger Federer has mixed feelings about mid-match interviews. On Monday, Coco Vandeweghe was interviewed by ESPN during her match.
Victoria Azarenka to the umpire: "Have you ever played tennis? You probably weren't very good."
"I don't think any of us in this room right now were perfect at 20. Speak up if you were…. thought not." Nick Kyrgios points out that he is not the first 20-year-old to slip up.
"When he let go of the racquet today after the forehand, I mean, that only happens to him. It went into the crowd." Andy Murray admits he cannot help but laugh sometimes when watching the Kyrgios antics.
"Who am I playing?" Stan Wawrinka, who defeated Albert Ramos 7-5 6-4 7-6 (8-6), needs a bit of help when asked to discuss his next opponent.