• US Open

Murray admits to failing physically in Djokovic defeat

Andy Murray admitted Novak Djokovic was fitter than him during the final two sets of their US Open quarter-final © AP

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Andy Murray avoided another bout of cramp but said he just could not match Novak Djokovic's fitness in the latter stages of his marathon four-set quarter-final defeat at the US Open.

The world No.9, who beat Djokovic over five sets and four hours to claim his first grand slam in New York in 2012, faded in the third and fourth sets as he struggled with stiffness in his back and hips in a match that lasted three hours and 32 minutes.

"Physically he was better than me in the end," admitted Murray. "He appeared fresher than me. Whether he was or not I don't know, but maybe he does a better job of hiding it than me."

For two sets Murray produced some of the best tennis since undergoing back surgery towards the end of the 2013 season but faded in the third as his legs became heavy.

"The pace of my serve slowed significantly towards the end of the third set," Murray said. "Over the course of the match he was a little bit more solid than me."

Djokovic has now won 13 of the pair's 21 encounters to return to the semi-finals of the US Open for an eighth consecutive season.

For his part, Murray was not surprised to find himself embroiled in his most demanding test of the season.

"Physically it's extremely demanding," Murray said. "We have had a lot of tough battles, mainly in the slams, but even outside of them as well. You need to be on it physically and mentally for a long period of time if you want to beat him."

The world's top eight players over the course of the year will head to The O2 in November for the season finale, the Barclays ATP World Tour Finals.

Murray is currently ninth in the race, with 10th-placed Kei Nishikori set to collect more points after reaching his maiden grand slam semi-final in New York.

Murray has qualified for the event every season since 2008. Djokovic, Rafael Nadal and Roger Federer have already qualified for the 2014 edition, but the Scot refused to consider adding to his schedule before the season ends.

"I don't want to overplay," Murray insisted. "I'll play the right schedule. I'll likely play a tournament before Shanghai, I'm not sure exactly which one yet. I won't expect to overplay just to try to qualify."

Even in defeat, Murray found positives from a US Open campaign that began with a bizarre cramping episode in his first-round match and ended with him pushing the world No.1 before bowing out in four sets.

"I don't feel particularly proud right now, I feel disappointed," he said. "But I think there was some good tennis. I obviously haven't analysed the match or had time to think about it yet, but I think there was some good tennis there. Hopefully I can build on that."

© ESPN Sports Media Ltd