Novak Djokovic
Djokovic into semi-final after seeing off tired Murray.Getty

Novak Djokovic defeated Andy Murray to reach the semi-finals of the US Open after a gripping four-set victory at Flushing Meadows.

Murray was given a stern examination by the world number one who sealed a 7-6 (7-1) 6-7 (1-7) 6-2 6-4 victory in just over three and a half hours.

After his success at Wimbledon this summer Djokovic is now on course back to back major titles and will meet 10th seed Kei Nishikori in his semi-final on Friday.

Despite his admirable effort against the Serb, defeat continues Murray's unwanted record of having failed to get past the semi-finals of any tournament since his return from surgery this time last year.

Djokovic stormed to a 4-1 lead in the opening set as the world number one clinically dispatched break points at the Arthur Ashe Stadium. Murray however clawed his way back into the contest, prevailing in an absorbing rally that he clinched just inside 30 shots. But with a tiebreak forced, Djokovic's unerring serve returned as he prevailed 7-1 to seal the first set.

Murray began the second with a double fault before netting a backhand and a forehand, again handing the advantage to the world No.1. But the 2012 champion regained a footing in the contest, sending Djokovic sprawling across the baseline with deep forehands to force another tie break.

This time around it was Murray who dominated, forcing Djokovic into a string of errors as the Scot sealed a reverse of the first set's tiebreak.

As the contest past the two hour mark, signs of fatigue began to break into Murray's game. A loose service game from the 27-year-old allowed Djokovic to march into the lead once again and consecutive netted efforts allowed him to break again in a set that matched the intensity of the first two.

Into the fourth, Murray had to hold serve to keep the match alive but Djokovic continued his march to the final with two match points to send the Scot packing.