British number one Kyle Edmund exited the US Open in the first round after a surprise loss to Italy’s Paolo Lorenzi.
Lorenzi, the world number 94, beat the 16th seed 4-6 6-4 7-5 6-1 amid high humidity at Flushing Meadows.
After taking the opening set, Edmund, 23, was pegged back in the second before he cramped up in the third, affecting his movement on court.
The match, which lasted three hours and 12 minutes, was played in temperatures of 30C and with humidity above 60%.
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Edmund struggled as his fitness problems took hold in the third set, and he had to stretch out his groin repeatedly.
A series of double faults from 36-year-old Lorenzi kept a wincing Edmund in the set, but the longer it went on, the more the momentum shifted towards the unseeded Italian.
Edmund, shaking his head, did not even attempt to play a shot as Lorenzi closed out the set in the 12th game with a backhand, before the Briton called on the trainer for treatment.
He was given salts in a bid to combat the problem, but his movement continued to be restricted.
Although the veteran Lorenzi does not have a powerful serve, his tally of 21 aces – including eight in the final set – is an indicator of how Edmund struggled to move as the match wore on.
Cramp problems return for Edmund
Cramping was an issue which Edmund struggled with earlier in his career, notably during the 2015 Davis Cup final and again a few months later during an opening-day exit at the 2016 Australian Open.
And the problem returned at the most inopportune time at Flushing Meadows.
British women’s number four Naomi Broady, commentating for BBC Radio 5 live sports extra, said she was “a bit lost” why cramp would return to affect Edmund.
“My only assumption is something wasn’t right with his hydration in the past 24-48 hours,” she said.