NEW YORK (AFP) — Novak Djokovic and Carlos Alcaraz are on a US Open collision course as the final Grand Slam tournament of the season gets under way with American teenager Coco Gauff chasing a breakthrough first major title.

A little more than six weeks after world number one Alcaraz defeated Djokovic in an enthralling finale to the Wimbledon championships, the two men could meet again at Flushing Meadows if the seedings go to play over the next fortnight.

Djokovic and Alcaraz whetted the tennis world's appetite for another blockbuster showdown at the Cincinnati Open last week, with 23-time Grand Slam singles winner Djokovic downing the 20-year-old Spaniard in a four-hour classic.

Djokovic, 36, is making a long-awaited return to the US Open this year after his refusal to be vaccinated against Covid-19 meant he was unable to gain entry to the United States.

In Djokovic's absence at last year's tournament, Alcaraz announced his arrival on the world stage with a brilliant run to his first US Open crown.

Second seed Djokovic, who opens his campaign on the Arthur Ashe main arena against France's Alexandre Muller on Monday, said Alcaraz's relentless, swashbuckling style is reminiscent of Rafael Nadal, the 22-time Grand Slam singles champion who missed this year's US Open due to injury.

"Each point is a hustle. Each point is a battle. You feel like you're not going to get maybe in total five free points in the entire match," Djokovic said of Alcaraz.

"You've got to basically earn every single point, every single shot, regardless of the conditions."

Alcaraz, who faces Germany's Dominik Koepfer in the first round on Tuesday, said he is flattered by the Nadal comparison.

"It's great that he knows that every time he's going to play against me, it reminds him of playing against Rafa or against the best ones because that means we are on a good path," he said.

Djokovic will reclaim the world No. 1 ranking with a victory over Muller on Monday, regardless of how Alcaraz performs in the tournament.