Novak Djokovic is through to the US Open semi-finals after beating Andy Murray in four thrilling sets.

Djokovic endured in a three-hour and 32-minute slug-fest to win 7-6 (7-1), 6-7 (7-1), 6-2, 6-4 at Arthur Ashe Stadium on Thursday (AEST).

The Serb took a one-set lead after winning a tie-break in a furiously contested opening exchange, only to see Murray level the match in another tie breaker in the second set.

Both players exchanged breaks of serve in each of the first two sets, but Murray had looked to get the upper hand as he breezed to a 7-1 tie-break win to level the match up.

But as soon as Murray had looked to have found his rhythm, Djokovic stormed back into the lead with an electric display of attacking tennis to convincingly win the third set 6-2 after breaking the Briton’s serve twice.

Djokovic and Murray both held serve throughout the fourth set, until a tiring Murray faltered in his final service game as Djokovic broke to seal the win.

The match was the first time in the tournament so far that Djokovic had dropped a set, as the number one seed continued his ominous form to live up to his pre-Open favouritism.

Djokovic will meet Japan’s Kei Nishikori in the semi-finals after the Japanese 10th seed beat Stanislas Wawrinka in five sets, fresh after surviving a marathon fourth-round encounter with Milos Raonic.