NEW YORK (AFP) — Novak Djokovic ensured he will return to the top of tennis's world rankings with an emphatic first-round victory in the US Open as women's world No. 1 Iga Swiatek and American rival Coco Gauff advanced.

Chasing a record-extending 24th Grand Slam singles title in New York, Djokovic shrugged off a late-night start on the Arthur Ashe Stadium to demolish France's Alexandre Muller 6-0, 6-2, 6-3 in just one-hour and 35 minutes.

The win means Djokovic is guaranteed to replace defending US Open champion Carlos Alcaraz as world No. 1 when the tennis rankings are next updated after the tournament.

Djokovic is playing in New York for the first time since suffering an agonizing defeat in the 2021 final in New York.

He was barred from entry to the United States in 2022 for his refusal to get vaccinated against Covid-19, meaning he was unable to play the US Open.

On Monday, the 36-year-old played like a man making up for lost time, reeling off 32 winners and breaking Muller eight times in a lopsided encounter that finished at around 12:40 a.m. local time.

Djokovic, who will face Spain's Bernabe Zapata Miralles in the second round, said he was unfazed by the late start to his game.

"I didn't care if I started after midnight because I was looking forward to this moment for a few years, to be out on the biggest stadium in our sport, the loudest stadium in our sport, playing a night session," Djokovic said.

"It was a great joy to be stepping out on the court."

"I think the performance explains how I felt tonight, particularly in the first two sets. It was kind of lights-out tennis really, almost flawless, perfect first set."

"Overall, I'm very, very pleased with the way I feel, with the way I'm playing. Hopefully, I can maintain that level."

Djokovic's arrival on court had been delayed after a grueling three-set battle between American teenager Gauff and Germany's Laura Siegemund in the preceding night game.