After 13 months without a title, the 27-year-old Scot insisted he is now totally injury-free and looking forward to returning to the New York courts where he won his first Grand Slam in 2012.
The world No 9 said: "I feel good. I have had a great practice week, had good fun on the court, enjoyed it, and worked hard.
"I've been playing well the last few weeks. I lost to guys who'd won the events and had big opportunities in both those matches. This week has been very good preparation. "
Looking relaxed, Murray smiled when asked to comment on his mum Judy's announcement that she'll be taking part in the BBC show Strictly Come Dancing later this year.
"If it makes her happy, I'll support her. I'm not really into those shows but she loves it," he said, grinning broadly. "I mean, she watches it all the time, talks about it all the time.
"Will I be watching? Probably not. I don't believe I have ever seen her dance, to be honest."
Murray begins his bid for a second US Open title tomorrow against 27-year-old Dutchman Robin Haase, who admits his knees belong to "a 60 or 70 year old". Yet the world No 70 will believe anything is possible after having taken the Scot to five sets at Flushing Meadows in 2011.
Haase, who conceded injuries have come close to wrecking his career, was just as frank about his surprise at seeing Murray sign up Amelie Mauresmo as coach to replace Czech legend Ivan Lendl.
"I wouldn't have a woman as a coach," he said. "In the end you need to understand how the game works and women's tennis and men's tennis are such different games.
"For me it's a surprise that many players work with ex-tennis players now. I wouldn't work with a former professional who has no experience as a coach."