World No.1 Novak Djokovic has reached an eighth successive US Open semi-final, downing Andy Murray 7-6 (7-1) 6-7 (1-7) 6-2 6-4 to set up a clash against Kei Nishikori for a place in the final.

Djokovic, the 2011 champion, clinched his 50th win in New York and 13th in 21 meetings with 2012 champion Murray in an early morning finish on Thursday.

Nishikori, the 10th seed, had earlier defeated Australian Open champion Stan Wawrinka 3-6 7-5 7-6 (9-7) 6-7 (5-7) 6-4 to become the first Japanese man in the semi-finals in New York in 96 years.

Nishikori, the 24-year-old 10th seed, triumphed in four hours 15 minutes, his second marathon clash after needing four hours 19 minutes to get past Milos Raonic in the previous round.

Ichiya Kumagae was the last Japanese man to reach the semi-finals of the US Championships in 1918.

Nishikori was stunned by his win over the third seeded Wawrinka, who had won the pair’s two other meetings without dropping a set.

“I was tight at the start but my body was OK. I felt more confident after the first set,” said Nishikori, who will be playing in his first grand slam semi-final having made the quarter-finals at the Australia Open in 2012.

“It feels amazing. I am playing well and I hope to play at 100 per cent in the semi-finals.”