Defending champion Murray advances to US Open last eight

Andy Murray battled blustery conditions to progress to the US Open quarter-finals with a four set victory over Uzbekistan's Denis Istomin.

The defending champion recovered from narrowly losing a first set tie-break to advance 6-7, 6-1, 6-4, 6-4 and will now take on Switzerland's Stanislas Wawrinka in the last eight, after his win over fifth seed Tomas Berdych.

But Murray was far from his fluid best, struggling for consistency and frequently expressing his displeasure with some bad line calls at the Arthur Ashe Stadium.

"I wanted to just try and get through the match," he said. "In the end it was difficult conditions. It was extremely windy.

"He hits the ball pretty big and flat on both sides and it's hard at times to control. He made it very difficult for me.

"Hopefully I'll start playing a little bit better from now on

"I'm in the quarter-finals of a Slam. It's not an easy thing to do, and the matches are going to get tougher. I'll have to up my game."

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