Emma Raducanu's U.S. Open title defence ended at the first hurdle on Tuesday while Wimbledon champion Elena Rybakina and twice U.S. Open winner Naomi Osaka were also ousted in the opening round.

British teenager Raducanu made a dream run to the title as a qualifier last year but her return to court at Flushing Meadows was less memorable as she fell 6-3, 6-3 to Frenchwoman Alize Cornet.

"Obviously really disappointing. Really sad to leave here. It's probably my favourite tournament," Raducanu said. "In a way I'm happy because it's a clean slate... The target will be off my back slightly."

Rybakina became the latest top seed to exit the tournament after suffering a shock 6-4, 6-4 defeat by French qualifier Clara Burel while Osaka, unseeded this year, lost 7-6(5), 6-3 to Australian open finalist Danielle Collins.

"I tried as hard as I could. I wanted to play without my back being in pain. I only really started serving two days ago," said Osaka.

World number one Iga Swiatek cruised into the second round after crushing Italy's Jasmine Paolini 6-3, 6-0, but two-time U.S. Open winner Venus Williams bowed out after losing 6-1, 7-6 to Alison van Uytvanck of Belgium.

Rafael Nadal, returning to Flushing Meadows for the first time since winning the 2019 title, overcame an early scare to see off 21-year-old Australian wildcard Rinky Hijikata 4-6, 6-2, 6-3, 6-3.

Third seed Carlos Alcaraz, who became the youngest man to reach the quarter-final in New York a year ago, advanced after his Argentine opponent Sebastian Baez retired when the Spanish teenager was leading 7-5, 7-5, 2-0.

"Nobody wants to see a match end like this. Sebastian is a great player, fights to the last ball and deserves better things," said the 19-year-old.

After a gruelling 83-minute second set, world number 37 Baez called the trainer for a medical timeout but gave up the fight two games into the third set.

"Last year was one of the best moments of my life," said Alcaraz who reached the last eight in New York with a ranking of 54.

"It's a such a special place for me to play on the biggest stadium in our sport."

Azarenka, Kostyuk set for Belarus-Ukraine Open clash

Afp, New York

Belarus's Victoria Azarenka and Marta Kostyuk of Ukraine are set for a politically-charged US Open grudge match after advancing to a second-round showdown on Tuesday.

Former world number one Azarenka defeated Ashlyn Krueger of the United States in three sets while Kostyuk advanced to the second round with a straight sets win over Egypt's Mayar Sherif.

The results mean Azarenka and Kostyuk will face off against each other on Thursday against the backdrop of simmering recent player tensions caused by Russia's invasion of Ukraine.