World of sport: Murray beats Kyrgios, Wiggins rides Tour of Britain, Lancaster ignores Gatland mind games
Third seed Murray won 7-5 6-3 4-6 6-1 against the unpredictable 20-year-old in a thrilling night match in New York.
The Scot, who now faces Frenchman Adrian Mannarino on Thursday, said: “It was tough and I had to do a lot of running in very humid conditions
“I’m getting old now - 28 years old. I need to get in the ice bath and cool off a bit.”
Sir Bradley Wiggins has confirmed he will ride in the 2015 Tour of Britain, which starts on Sunday.
He will lead his own Team Wiggins in the road tour, before turning his attention to the track ahead of the 2016 Olympics in Rio.
Gatland suggested Wales were a much more settled side than their World Cup Pool A rivals England.
But Lancaster said: “Personally, I’d rather concentrate on our own stuff.
“We played lots of teams and different international coaches have different ways of preparing their team and preparing to play.”