Andy Murray's return to Grand Slam tennis ended in a four-set defeat by Spanish 31st seed Fernando Verdasco in the US Open second round.
The former British number one, playing his first Slam in 14 months, lost 7-5 2-6 6-4 6-4 in New York.
In sweltering conditions, Murray, 31, battled hard but did not have enough to overcome the 34-year-old Verdasco.
Compatriot Cameron Norrie lost 6-2 2-6 6-4 6-4 to Serbia's Dusan Lajovic as British singles representation ended.
It was only Murray's fifth tournament back since having hip surgery in January.
The Scot looked exhausted at times during a physical encounter on a humid Arthur Ashe Stadium - a combination of the conditions as temperatures rose close to 100F (38C) and his lack of five-set matches since being sidelined through injury.
Murray's limp between points - a regular sight in recent years - seemed to become heavier as the match wore on.
"It wasn't the most comfortable I felt on a tennis court. I got through it and fought right to the end," he said.
Murray continued to show the dogged determination that helped him win three Grand Slam titles at the peak of his powers, pushing Verdasco to the limit before succumbing to a third match point in three hours and 23 minutes.