Novak Djokovic dropped his first set of the US Open last night but recovered to beat Mikhail Youzhny and reach the semi-finals of a 14th consecutive grand slam.

The world number one was not at his very best, as he had been in a rout of Marcel Granollers on Tuesday, but he never looked in any real danger of following Andy Murray out of the tournament.

Russian Youzhny did well to take the third set before Djokovic hit back to win 6-3 6-2 3-6 6-0 and set up a last-four clash with Murray's conqueror Stanislas Wawrinka.

The first two sets were a story of missed opportunities for 21st seed Youzhny and a lesson in taking your chances from his opponent.

Youzhny had two break points in the opening game of the match, did not take them and then dropped his own serve to love.

The pair were sliding all around the court, playing some very entertaining points, but it was Djokovic in control.

He nearly blew it at 5-3, missing two set points and then giving up a break point, but again Youzhny could not capitalise.

Djokovic took his third chance, letting out a huge roar as he retrieved a Youzhny smash and forced the error.

The second set was also much closer than the scoreline suggested, but Djokovic won four of the first five games and did not let his advantage slip.

The Arthur Ashe crowd really appreciated Youzhny's efforts to take the game to his opponent, and it was the Russian's turn to roar when he finally took a break point in the fourth game of the third set to lead 3-1.

Djokovic pegged him back to 4-3 but then played a poor game, handing Youzhny another break with a double fault, which the Russian converted into the set.

That was as good as it got for Youzhny, though, Djokovic refocusing and not dropping a game in the fourth set.

There was one last hurrah for Youzhny with a superb down-the-line backhand winner on the run in the final game, but he celebrated in the manner of a man who knew the end was nigh.

Djokovic has won his last 11 matches against Wawrinka, but he would not have been happy with a tally of 45 unforced errors.