NEW YORK -- No. 11 Stefanos Tsitsipas' US Open woes continued as he suffered a 7-6 (5), 4-6, 6-3, 7-5 defeat to Thanasi Kokkinakis in the first round Tuesday.
After losing a close first set in a tiebreaker, Tsitsipas rallied to win the second and level the match, but he appeared to be bothered by an abdominal issue.
Tsitsipas, a two-time Grand Slam finalist, has never made it past the third round at Flushing Meadows.
He also struggled leading up to the tournament, winning just one of his three matches at the Canadian Open and Cincinnati Masters.
For Kokkinakis, it was his first win at the US Open since 2019.
"I had a five-set battle with him a couple of years ago at the Australian Open, and I was expecting a war," Kokkinakis said in his postmatch on-court interview. "It was physical out there, and I have a tendency to sometimes drag these matches on and have some real long battles, but I just tried to stay focused, stay the course and just tried to play every point."
He next faces either Nuno Borges or Federico Coria.
Jannik Sinner, the No. 1 seed on the men's side, played his opening-round match at Arthur Ashe Stadium and emerged with a 2-6, 6-2, 6-1, 6-2 win over Mackenzie McDonald.
It was Sinner's first action since word emerged that he had failed two drug tests in March but escaped suspension.
No. 19 Felix Auger-Aliassime was knocked out in the first round by 18-year-old Jakub Mensik, and No. 7 Hubert Hurkacz and No. 30 Matteo Arnaldi were among the men's winners.
No. 25 Jack Draper reached the second round after his opponent Zhang Zhizhen retired with a left leg injury in the third set with the Briton leading 6-3, 6-0, 4-0.
The Associated Press and Reuters contributed to this report.
