|2018 US Open|
|Venue: Flushing Meadows, New York Dates: 27 August-9 September Coverage: Live radio coverage on BBC Radio 5 live sports extra; live text commentaries on the BBC Sport website|
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.
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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.
Despite defeat, Murray felt he played some of his best tennis since returning to the ATP Tour in June.
"There were periods in the match where I played some really good stuff," he said.
"But there were some where I didn't - especially in the first set - and that was costly for me."
Murray sticks with Verdasco in hard-fought opening
Murray, now ranked 382nd in the world and unseeded, had the fortune of avoiding a high-ranked opponent in the first round, battling back to beat 448th-ranked James Duckworth - the Australian also on the road to recovery after long-term injury - in three sets on Monday.
That pitted him against two-time US Open quarter-finalist Verdasco, who Murray said he expected to test his movement - and the Spaniard did exactly that.
The pair traded four break points in the opening seven games, Murray missing a set point at 5-4 when Verdasco rescued it with an ace out wide.
That proved pivotal as Verdasco grabbed the momentum to break in the next game and hold out for the early advantage.
"I hit a lot of mistakes when I was up in that set. I feel like I should have won the first set and didn't," said Murray.
Murray was undeterred, however, breaking for 3-1 in the second set as Verdasco's service game began to unravel.
The pair exchanged breaks again as Murray moved 4-2 ahead before the Spaniard produced a double fault on set point to allow the former world number one to level.
Verdasco upped his service game in the third set, landing 71% of his first serves to break twice and ensure the match would go to four sets at least.
'I don't want to say Andy lied'
Both players disappeared off Ashe at the end of the third set after Verdasco took the 10-minute extreme heat break which was again implemented by US Open officials.
When Murray returned to court, he complained Verdasco was talking to his team in the locker room - which is against the rules.
"When I came out of the shower, his coach and one of the Spanish doubles players was in there chatting to him, and you're not allowed to speak to your coach. I went and told the supervisor," Murray said.
"I'm not blaming Fernando and his team. They probably weren't aware that that was the rules. They certainly weren't trying to break any rules.
"It shouldn't be for the player that's competing against him to have to go to the supervisor."
However, Verdasco denied he was talking to his coach, saying he was only there to go to the toilet.
"I was in the ice bath with Marcos Baghdatis and his coach," Verdasco said.
"I don't want to say that Andy lied, but I didn't talk one word with my coach or any one member of my team.
"I know exactly the rule and I don't want to be the one breaking it."
Murray refuses to give up as Verdasco wobbles over the line
After the heat break, a composed Verdasco controlled the fourth set and headed towards victory after breaking for 4-3.
That was until an 11-minute final game when the Spaniard combusted with a third-round match against Argentine third seed Juan Martin del Potro in sight.
His previously reliable serve disappeared as he coughed up five break points, produced two double faults and hit some wild shots in a dramatic final game.
Verdasco also furiously complained after being given a time violation before eventually ending Murray's resistance with a 104mph second serve - his fastest of the match - which forced Murray long on the third match point.
"At the end when my back was against the wall, I came up with some good tennis to make it close and interesting and almost got myself back into it," Murray said.
"But there were too many ups and downs for my liking."
Encouraging, but a long road ahead - analysis
BBC tennis correspondent Russell Fuller
These three hours and 23 minutes reminded us exactly what we have been missing.
Murray offered flair, heart and resilience, mixed in with a familiar dose of confrontation and a long-running one way 'conversation' with his coach Jamie Delgado.
Even when seemingly running out of gas in the fourth set, he still managed to create five break back points in a final game which lasted over 12 minutes.
Unsurprisingly, so soon in his comeback, Murray's unforced error count was higher than he would wish for. But in the early stages especially, he played as close to the baseline as possible, and significantly inside it when Verdasco lined up a second serve.
It has been an encouraging US Open, but Murray knows there is still a long road ahead.
Norrie fails to take his chances
British number two Cameron Norrie's bid to reach the third round of a Grand Slam for the first time came to an end only moments after Murray's defeat.
The 23-year-old world number 67, who has enjoyed a rapid rise up the rankings since turning professional in spring 2017, was not helped by his 58 unforced errors against Lajovic.
His match mirrored Murray's as he fought back from a set down to take the second before failing to take his chances in the next two sets - managing to convert just three of his 14 break points in a match lasting almost three hours.
Norrie was also penalised a first serve for returning late from the 10-minute heat break after the third set. The unhappy Briton told the umpire he had been assured by officials he had enough time.
Defeat for Norrie and Murray means there are no Britons left in the men's or women's singles after Kyle Edmund, Johanna Konta and Heather Watson were knocked out in the first round.
Meanwhile, in the men's doubles British brothers Ken and Neal Skupski were beaten 7-6 (7-4) 7-6 (7-5) by Radu Albot and Malek Jaziri.