Former world No.1 Andy Murray has denied James Duckworth the biggest win of his career with a hard-earned four-set US Open win over the plucky Australian.

Making his grand slam comeback after almost a year out of tennis, Murray battled back from a set down to defeat Duckworth 6-7 (5-7) 6-3 7-5 6-3 in a sapping first-round encounter played in brutal New York heat.

“I played a decent match,” Duckworth said.

“Played an aggressive style. The things that let me down today were probably my serve and return.

“My first-serve percentage wasn’t good enough and I didn’t feel like I returned great, especially his second serve, which probably hurt me in the end.”

Established in the world’s top 100 three years ago before needing five surgeries in 12 months to save his career, Duckworth will depart New York with renewed belief.

“I can take confidence from this. I’m slowly sort of building,” the 26-year-old said.

“There’s still a fair way to go with my game and just being able to sustain a level physically for extended periods of time.

“But I’ve got no injury concerns, which is nice.

“I’m going to play just Challengers for the rest of the year and try and win as many matches as I can and get that ranking climbing.”

Contesting his first grand slam event in 14 months, Murray next faces Spanish veteran Fernando Verdasco as he continues his own revival following hip surgery last year.

“I’m still just taking it one match at a time. I mean, this is the first time I have played four sets in 14 months,” the 2012 champion in New York said.

“I just have to wait and see how I pull up tomorrow. Hopefully I feel good and take it from there.”