Emma Raducanu's US Open title defence ended at the first hurdle on Tuesday while Wimbledon champion Elena Rybakina and twice US 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.
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.
0432 COLLINS OUSTS OSAKA
Two-time US Open champion Naomi Osaka fell 7-6(5) 6-3 to Australian Open finalist Danielle Collins, who fought back from a break down in both sets to reach the second round.
0412 SCHWARTZMAN THROUGH AFTER SOCK RETIRES INJURED
Argentine 14th seed Diego Schwartzman advanced to the second round after his American opponent Jack Sock retired with an injury while leading 6-3 7-5 0-6 0-1.
0228 NADAL HOLDS OFF HIJIKATA
Four-time US Open champion Rafael Nadal recovered from a set down to beat Australian wildcard Rinky Hijikata 4-6 6-2 6-3 6-3, staving off a late fightback from the 21-year-old before closing out the win with a blistering forehand winner down the line.
Nadal, making his first appearance at Flushing Meadows since winning the 2019 title, will take on Italian Fabio Fognini in the second round.
0142 SHAPOVALOV GRINDS OUT FIVE-SET WIN
Canadian 19th seed Denis Shapovalov earned a hard-fought 2-6 6-4 6-4 3-6 6-1 victory over Marc-Andrea Huesler of Switzerland in a match that lasted almost three hours.
0140 AZARENKA BATTLES PAST KRUEGER
Belarusian Victoria Azarenka, a three-time US Open finalist, was 6-1 3-0 up in the second set before letting her lead slip against American qualifier Ashlyn Krueger but bounced back in the decider to clinch a 6-1 4-6 6-2 victory.
Azarenka will face Marta Kostyuk of Ukraine in the second round.
0122 RADUCANU KNOCKED OUT BY CORNET
Defending champion Emma Raducanu was knocked out in straight sets by Alize Cornet, going down 6-3 6-3 to the Frenchwoman.
Cornet is playing in her 63rd consecutive Grand Slam main draw, a record in the Open era.
0113 KENIN KNOCKED OUT, FOGNINI RALLIES TO VICTORY
Sofia Kenin, the 2020 Australian Open champion, was knocked out in straight sets by Wimbledon quarter-finalist Jule Niemeier who came away with a 7-6(3) 6-4 victory.
Fabio Fognini was the third Italian to play a five-setter on Tuesday, mounting a comeback from two sets down to beat Aslan Karatsev 1-6 5-7 6-4 6-1 6-4. Both players made over 60 unforced errors and were broken 13 times in total.
0025 GOFFIN CRUMBLES UNDER MUSETTI PRESSURE
Italy's Lorenzo Musetti fought back from 2-5 down in the final set to beat Belgian David Goffin 3-6 7-5 6-4 3-6 7-6(9) in a match that lasted 4-1/2 hours.
0006 QUERREY MAKES FIRST ROUND EXIT
Sam Querrey, playing in his last tournament before retirement, became the latest American to make a first round exit, losing 4-6 6-4 7-6(8) 6-3 to Belarusian Ilya Ivashka.
2350 HURKACZ, BADOSA ADVANCE
Eighth seed Hubert Hurkacz had no problems dispatching Oscar Otte, who did not have a single break point opportunity in a 6-4 6-2 6-4 defeat.
Women's fourth seed Paula Badosa survived an early scare to beat Lesia Tsurenko 3-6 7-6(4) 6-3.
2245 RUBLEV AND SINNER STRETCHED TO FIVE SETS
Russian ninth seed Andrey Rublev blew a two-set lead against Laslo Djere and was made to work hard for his 7-6(5) 6-3 3-6 4-6 6-4 victory in a match that lasted more than 3-1/2 hours.
Italian 11th seed Jannik Sinner's first round match also lasted over 3-1/2 hours as he outlasted Germany's Daniel Altmaier 5-7 6-2 6-1 3-6 6-1.
2108 VAN UYTVANCK KNOCKS OUT VENUS WILLIAMS
Belgian Alison Van Uytvanck beat 42-year-old Venus Williams 6-1 7-6(5) to advance to the second round, a day after the American's sister and doubles partner Serena advanced.
"It's always an honour to play a legend. ...I was so happy to play her on Arthur Ashe, I had goosebumps," Van Uytvanck said.
1936 RYBAKINA KNOCKED OUT BY QUALIFIER
Wimbledon champion Elena Rybakina was knocked out in straight sets by French qualifier Clara Burel, going down 6-4 6-4 after making 37 unforced errors.
1850 STEPHENS LEADS AMERICAN CHARGE
Former champion Sloane Stephens fought back from a set down to beat Greet Minnen 1-6 6-3 6-3 at Louis Armstrong Stadium.
In the men's draw, Americans John Isner and Brandon Nakashima advanced with straight sets wins over Federico Delbonis and Pavel Kotov, respectively.
1844 ALCARAZ THROUGH AFTER BAEZ RETIRES INJURED
Third seed Carlos Alcaraz advanced to the second round after his Argentine opponent Sebastian Baez retired with an injury when he was down 7-5 7-5 2-0.
"Nobody wanted to see a match end like this... Sebastian's a great player, he fought until the last point," Alcaraz said.
1749 PLISKOVA, PEGULA AND MUGURUZA ADVANCE
Former world number one Karolina Pliskova overcame Magda Linette 6-2 4-6 7-6(8) in a match where there was little to separate the two players until the final set tiebreak.
American eighth seed Jessica Pegula beat Viktorija Golubic 6-2 6-2 while twice Grand slam champion Garbine Muguruza also advanced in straight sets beating Clara Tauson 6-3 7-6(5).
1657 SWIATEK CRUISES INTO SECOND ROUND
World number one Iga Swiatek handed Jasmine Paolini a bagel en route to reaching the second round, as she eased past the unseeded Italian 6-3 6-0 in 67 minutes.
Joining her was American eighth seed Jessica Pegula who beat Viktorija Golubic 6-2 6-2 and sixth-seeded Belarusian Aryna Sabalenka after her 6-1 6-3 win over Catherine Harrison.
1506 PLAY UNDER WAY
Play began in New York with the temperature hovering around 28 degree Celsius (82.4 degrees Fahrenheit).