Andy Murray says he "might need to accept" a long-awaited deep run at a Grand Slam may not ever come after his latest effort was ended in the US Open second round.

Former world number one Murray, 36, lost 6-3 6-4 6-1 against 19th seed Grigor Dimitrov in New York.

Murray, ranked 37th, has not reached the last 16 of a major since resuming his career after hip surgery in 2019.

"It's unbelievably challenging to play at the highest level," he said.

"It's obviously disappointing to not play how you would like.

"Maybe I need to accept the deep runs and everything that I felt I'm capable of, they might not be there."

Murray still enjoying 'the work' despite setbacks

Putting together a run at a major was Murray's prime target this season as the three-time Grand Slam champion continues in the twilight of his career.

The Scot reached the Australian Open third round in January and, after skipping the French Open, lost in the Wimbledon second round last month.

Despite these setbacks at the majors, Murray has continued on an upward trajectory and recently moved up to his highest ranking since his comeback four years ago.

"I still enjoy everything that goes into it. I enjoy the work, the training and trying to improve and trying to get better," said Murray, who reached the Doha final in February and has won three titles on the second-tier ATP Challenger Tour this year.

"That's what keeps me going.

"If I stop enjoying that - or my results, my ranking and everything starts to go backwards, if in a few months' time I was ranked 60 in the world or whatever instead of moving up - things might change."

Going into the four Grand Slam events with a seeding would, on paper, make going further at the majors a stronger possibility.

Those ambitions were hindered by the Scot pulling out of tournaments in Toronto and Cincinnati this month because of an abdominal injury.

Falling narrowly short of the top 32 going into the US Open did not help his chances in New York.

Having recovered from the injury, Murray played well in his opening-round win over France's Corentin Moutet but his level dropped considerably against the wily Dimitrov.

"If I want to have deep runs in these tournaments, I'm going to have to come up against players like Grigor," said Murray, who lost to fifth seed Stefanos Tsitsipas in the Wimbledon second round.

"Whether I was seeded or not here in the top 32, I don't think that guarantees I'm going to have a deep run either."

Dimitrov tactics disrupt Murray

A lot of credit must go to former world number three Dimitrov - coached by Dani Vallverdu, who used to work with Murray - for executing a clear gameplan which set out to frustrate the Briton.

Dimitrov's backhand slice regularly took the pace out of the rallies, forcing Murray to trade from the back of the court and making the contest physical with some long duels.

Murray was always chasing after being broken in his first service game of each set, while he was only able to convert two of the nine break points he created.

It became a tough watch for those on Arthur Ashe Stadium supporting Murray, who remains a popular figure at the place where he won the first of his three major titles.

After falling a double break behind in the third set, Murray gave a gesture towards his team indicating he was finished and his troubles were encapsulated by a double fault on a third match point for 32-year-old Dimitrov.

Dimitrov, who reached the US Open semi-finals in 2019, will play German 12th seed Alexander Zverev in the last 32.

Murray, meanwhile, said he will fly home to the UK as quickly as possible and indicated he might not play for Great Britain in next month's Davis Cup tie in Manchester.

"If I'm being honest, the other guys deserve to play ahead of me," said Murray, who suggested Jack Draper should play instead.

"I think there is probably a chance that I'm not on the team. I'll try to get home this evening or tomorrow morning, then see where I go from there."