US Open: Andy Murray says Novak Djokovic match demanding

Britain's Andy Murray said he was disappointed that Novak Djokovic proved physically stronger in their US Open quarter-final.

The 27-year-old lost 7-6 (7-1) 6-7 (1-7) 6-2 6-4 over three hours and 32 minutes at Flushing Meadows.

"I thought physically he was better than me in the end," said Murray, the eighth seed.

"I was a little bit disappointed, to be honest, because I did train very hard."

Murray carried out a training block with his support team in Florida after a disappointing quarter-final defeat at Wimbledon in July.

"You do the work for these matches, so I would have liked to have felt a little bit better towards the end," said the Scot.

Djokovic, 27, also felt he had an advantage when he faces Murray in Grand Slam matches over the best of five sets.

"I get the feeling that if I get to stay with him and work, and not get too loose and too frustrated with points, and not allow him to get into a big lead, I feel like there is a point where I have that edge physically," said the Serb.

"That's what I try to always focus on and it paid off tonight."

Murray, who underwent back surgery following last year's US Open and missed the final months of the 2013 season, described playing Djokovic as extremely demanding.

The Briton has made at least the quarter-finals of all four Grand Slams this year, but found the world number one a step too far.

"Maybe I haven't played enough matches at that level this year," he said.

"It's obviously different playing at that level, playing against the number one in the world. And the way that we play against each other, it's just an extremely physical match.

Murray said that in games against other players, for example Roger Federer, the points come quicker and it is not as demanding.

He added: "When me and Novak play against each other, you obviously see very tight, long rallies. Both of us do a lot of running.

"Maybe I'll gain a lot from playing a match like today, because it doesn't matter how much training you do, when you get on the match court it's different.

"I can't practise with the best player in the world, so it's tough to practise at that intensity."

Murray had spent three-and-a-half hours longer on court than Djokovic on his way to the last eight

Murray needed treatment from the trainer in the fourth set but played down the issue.

"I got stiff in my hips and my back towards the end of the third set," he said. "I don't know exactly why. I'm certainly not injured. I didn't hurt anything.

"It was just fatigue I think and I stiffened up towards the end of the third set."

Murray now faces a challenge to qualify for the ATP Finals in London, as he stands ninth in the race, with the top eight making the cut.

"To be honest, it was not a massive goal of mine," he said.

"It's obviously nice to qualify for it. It's a good tournament. I played a number of years, and enjoyed it. But I don't want to overplay. I'll play the right schedule."

After twice breaking Murray in the first set, Djokovic eventually took the set with a convincing tie-breaker

Andy Murray battled from 3-1 down in the second set to win the tie-breaker

Djokovic converted seven of 10 break points in the match

Djokovic will play in his eighth consecutive US Open semi-final