Former champion Carlos Alcaraz was dumped out of the U.S. Open in a stunning straight-sets defeat by world number 74 Botic van de Zandschulp on Thursday, while top seeds Jannik Sinner and Iga Swiatek moved on to the third round with little fuss and Naomi Osaka madde exit from second round.
Spanish third seed Alcaraz was fully expected to extend his 15-match winning streak at the Grand Slams but the Wimbledon and French Open champion got off to a horrible start and never recovered, going down 6-1 7-5 6-4 in the second round.
Van de Zandschulp, the first Dutchman to defeat a player in the top three at a major since Richard Krajicek beat Pete Sampras in the 1996 Wimbledon quarters, will next play Britain's Jack Draper.
"It was a fight against myself, you know, in my mind during the match. In tennis you are playing against someone that wants the same as you," said Alcaraz.
"Today I was playing against the opponent, and I was playing against myself."
There was far less drama earlier in the day at Arthur Ashe Stadium, where Poland's Swiatek swatted aside Japanese qualifier Ena Shibahara 6-0 6-1 in a little over an hour. She plays unseeded Russian Anastasia Pavlyuchenkova next.
Australian Open winner Sinner was similarly untroubled in dispatching American Alex Michelsen 6-4 6-0 6-2, taking just 99 minutes to complete his ATP Tour-leading 30th hardcourt win of the year.
The Italian, who will play Australian Chris O'Connell next, has been dogged by controversy at Flushing Meadows after it was revealed days before the tournament he escaped a ban and was cleared of wrongdoing despite failing two drug tests this year and he fired both his physio and trainer last week.
Twice champion Naomi Osaka was sent packing by Czech Karolina Muchova 6-3 7-6(5), another disappointing Grand Slam exit in what she has dubbed her "learning year" after coming back from a 15-month maternity break.
Muchova, a semi-finalist last year, will next play Russian Anastasia Potapova.
Former champion Daniil Medvedev moved past Hungarian Fabian Marozsan 6-3 6-2 7-6, helped by his opponent's 45 unforced errors, and will next play Italian Flavio Cobolli.
Sixth seed Jessica Pegula and 14th seed Tommy Paul boosted home hopes as both Americans advanced to the third round but compatriot Sebastian Korda crashed out.
Defending champion Coco Gauff will hope to keep the good times rolling for the home crowd when she opens up the action at Arthur Ashe against Ukrainian Elina Svitolina on Friday.
Ben Shelton and Frances Tiafoe promise fireworks in an all-American third-round clash.
