Novak Djokovic said he was happy with the intensity he showed in Sunday's US Open fourth-round win over Kyle Edmund despite his unusual preparation.

The defending champion in New York had a bizarre route to the last 16, spending just over three hours on court in the previous three rounds.

Djokovic was the beneficiary of a walkover and retirement in the second and third rounds respectively heading into the clash with Edmund. 

But the world number one showed little sign of rustiness, advancing to the quarter-finals with a 6-2 6-1 6-4 victory over the Briton, despite requiring treatment on his right arm.

"Obviously I haven't played too much tennis. So I'm really glad to be back," Djokovic said in his on-court interview.

"I thought I came out, really, from the blocks very good, playing with a high intensity.

"I made Kyle work for each point. I wanted to move him around the court."

The win means Djokovic will face Jo-Wilfried Tsonga - who has lost 15 of the 21 previous meetings between the pair - for a spot in the semi-finals.

"I think it's great that I get to play a night session tonight," Djokovic said. "Midnight delight. And hopefully there will be another delight in a couple of days, but it's going to be obviously tough against Jo, who has been playing some great tennis.

"He dropped only one set en route to the quarter-finals so I'm looking forward to that one. I had some great matches against him in the past."