Emma Raducanu is still waiting for her first US Open victory since her memorable 2021 triumph after again being knocked out in the first round.
The 21-year-old surprised the world three years ago when she won the title at her third senior tournament, but it has not been a success since then.
After being knocked out in the first round in 2022 and battling an injury last year, Sofia Kenin added to the misery with a 6-1, 3-6, 6-4 victory on the Grandstand court.
It looked like it would be a short performance as Kenin played the first set at breakneck speed, but Raducanu made a mess of it by throwing the set into three sets.
A precious service game midway through the deciding match proved costly as the former champion headed home a goal.
Emma Raducanu was knocked out in the first round at the US Open, losing to Sofia Kenin
Raducanu, 21, was on court for two hours and eleven minutes but lost the match in three sets
She has only played in one tournament since Wimbledon, and skipped the Olympics to focus on her preparation for the US Open. She will be hugely disappointed if she falls at the first hurdle. Questions remain about the direction of her career.
In her defence, I have to say it was a tough draw for Raducanu against a former Australian Open winner who was showing some of her best form.
Kenin was taken with Raducanu’s serve and broke three times en route to a dominant first set.
Sofia Kenin advances to the second round to face either Shelby Rogers or Jessica Pegula
Raducanu has been struggling with a series of injuries all year and has not played much
The Briton had also missed three break points in the first set, but at the start of the second set she took a step forward by taking over Kenin’s serve.
The American immediately took back the break, but a crucial point at 2-2 and 15-15, in which Raducanu hit a winning backhand, turned the tide in the second set.
It helped her break, with Kenin losing her cool as she smashed the ball into the backboard. Two brilliant winners saw Raducanu take a second break and the second set in style.
But in the fifth game of the deciding match, things went wrong for the Briton. She was broken and there was no way back. Kenin held on clinically.