World No.1 Novak Djokovic has advanced to the US Open final with a four set victory over Frenchman Gael Monfils.

Djokovic took the match 6-3 6-2 3-6 6-2 as both men battled through the sticky New York heat.

Monfils dug deep to push the match to a fourth set as he battled through injury in the humid conditions but was unable to match the Serb in the final set.

The winner will play either Japan’s Kei Nishikori or Swiss star Stan Wawrinka in the final.