Iga Swiatek and Carlos Alcaraz reached the second round of a sweltering US Open on Tuesday as former champions Rafael Nadal and Naomi Osaka prepared to light up the New York night.

World number one and French Open champion Swiatek eased past Italy's Jasmine Paolini 6-3, 6-0 in just 67 minutes.

Victory was a relief for the 21-year-old Pole who had suffered early losses at warm-up events in Toronto and Cincinatti.

"In matches, being a little bit stressed and tight, it can get a little bit worse, but still, I feel like my level is just better," said Swiatek.

"We'll see if I'm going to hold on to that."

Alcaraz, the 19-year-old world number four, was made to sweat by battling Sebastian Baez, winning the first two sets 7-5, 7-5 before the Argentine retired injured 0-2 down in the third.

"Nobody wants to see a match end like this. Sebastian is a great player, fights to the last ball and deserves better things," said Alcaraz, a quarter-finalist in 2021.

As the temperature soared beyond the 30-degree mark, Wimbledon champion Elena Rybakina was the most high profile player to wilt.

The Kazakh lost 6-4, 6-4 to French qualifier Clara Burel, ranked a lowly 131, on the back of 37 unforced errors.

Britain's Cameron Norrie, the seventh seed, raced past France's Benoit Paire 6-0, 7-6 (7/1), 6-0.

Bizarrely, Paire started packing his bags at 0-5 down in the third set and he was a beaten man after only 98 minutes.

"Obviously it was really hot, and maybe towards the end of that third set he was playing really quick and trying to make the points really short, and maybe the heat was getting to him," said seventh seed Norrie.

The result made ugly reading for Paire who dropped the first set in just 18 minutes and the third in 19.

Sloane Stephens, the 2017 champion, defeated Greet Minnen of Belgium 1-6, 6-3, 6-3.

Czech 17-year-old Linda Fruhvirtova marked her main draw debut at the majors by seeing off Wang Xinyu of China 6-3, 6-4.

Later Tuesday, four-time champion Nadal begins his bid for a 23rd Grand Slam title and 20th win at the majors in 2022.

The 36-year-old Spaniard tackles Australian wild card Rinky Hijikata, ranked 191 and making his debut at the Slams.

Nadal comes into the tournament under an injury cloud after an abdominal strain forced him to forfeit his Wimbledon semi-final against Nick Kyrgios.

Since then, he has played just once, a first-up loss to Bornal Coric in Cincinnati.

"I take it very easy in the Cincinnati, too, in the practices. The match, I try my best without putting all the effort there on the serve," Nadal said on the eve of the US Open.

"I hope to be ready for the action. That's the only thing that I can say."

Despite his caution, Nadal remains a title favorite in his first appearance in New York since his 2019 title triumph.

His chances have been boosted by the absence of old rival Novak Djokovic who was banned from entering the United States over his refusal to be vaccinated.

Japan's two-time champion Osaka completes the night session on Arthur Ashe Stadium when she faces 19th seed Danielle Collins, this year's runner-up at the Australian Open.

Former world number one Osaka, the champion in New York in 2018 and 2020, is on a three-match losing streak in the US hard court season.

Osaka has won all three meetings against Collins without dropping a set.

The American arrives in New York having withdrawn from tournaments in San Jose, Toronto and Cincinnati with a neck injury.

Defending champion Emma Raducanu of Britain kicks off the night session on Louis Armstrong Stadium against France's Alize Cornet.

World number 40 Cornet is appearing in her 63rd consecutive Grand Slam, a new Open Era record, previously held by Ai Sugiyama of Japan.

After seeing Serena Williams stave off impending retirement by reaching the second round on Monday, big sister Venus eyes an 80th career win at the tournament.

Venus, 42, first played the US Open in 1997 where she finished runner-up.

Now ranked 1,504 in the world and without a win in just the three matches she has played in 2022, the American faces Alison van Uytvanck.