Seasoned champ v marathon man

NEW YORK - Novak Djokovic defeated Andy Murray to set up a US Open semi-final clash against Kei Nishikori, who became Japan's first semi-finalist in almost a century on Wednesday.

World No. 1 Djokovic, the 2011 champion, reached his eighth consecutive US Open semi-finals by downing Murray 7-6 (7-1), 6-7 (1-7), 6-2, 6-4 for his 13th win in 21 meetings against his childhood rival, who had taken the 2012 title.

Nishikori, the 10th seed, earlier took more than four hours to defeat third seed 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 96 years.

Wimbledon champion Djokovic and Murray had spent a record-equalling 4hr 54min contesting the 2012 final, and their quarter-final clash threatened to surpass that mark when they needed over two hours to get through the first two sets of a tie that started on Wednesday and finished early yesterday morning.

By the end, however, Murray was struggling with what appeared to be a recurrence of his longstanding back problem, a legacy of having spent 31/2 hours more on court than Djokovic in getting to this stage.

But victory was also a testament to the top seed's intimidating defensive skills, as he saved 12 of 16 break points in the 3hr 32min encounter, which saw Murray commit 65 unforced errors to Djokovic's 48.

"We both gave our best and, at times, the tennis was not nice, but that was due to the intense physical battle in the first two sets," said Djokovic.

"I didn't expect anything less from Andy. Our last few matches have been three and four hours, and he has a lot of quality on all sorts of surfaces.

"I knew it would be a tough match and that the more aggressive player would win."

Murray, still without a title since his historic Wimbledon triumph last year, said that he struggled as the match wore on.

"I tried my best to hang in there in the fourth set, but he was fresher than me or, at least, he appeared to be," said the Scot, who admitted that he felt stiffness in his hips and back as the night got cooler.

"The pace of my serve slowed significantly and he was a little more solid. I fought hard, but it wasn't enough."

Djokovic and Nishikori are 1-1 in career meetings, but their last clash was three years ago.

"It's great for Kei and Japan for him to be in the semi-finals. He serves and moves very well," said the 27-year-old Serb, who has made the final in New York in the last four years.

Nishikori, 24, triumphed over Australian Open champion Wawrinka in 4hr 15min, his second marathon clash after needing 4hr 19min 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, whose match against Raonic ended at a record-equalling 2.26am on Tuesday, was stunned by his win over 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 the Japanese, who will be playing in his first Grand Slam semi-finals, having made the quarter-finals in Australia in 2012.

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