NEW YORK, Sept. 7 (Xinhua) -- World number one Novak Djokovic survived a five-set battle to outclass ninth seed Stanislas Wawrinka 2-6, 7-6 (7-4), 3-6, 6-3, 6-4 on Saturday, reaching his fourth straight U.S. Open final.

The match lasted four hours and nine minutes. Two of the five sets had gone more than one hour and the longest game was played 21 minutes.

Djokovic, seeking his second Grand Slam title this season after winning the Australian Open, will face the winner of a later semi-final between 12-time Grand Slam champion Rafael Nadal of Spain and France's Richard Gasquet.