Nishikori to face Murray in Australian Open quarters

Japan's Kei Nishikori will be Andy Murray's surprise opponent in the Australian Open quarter-finals after a stunning five-set victory over former finalist Jo-Wilfried Tsonga on Monday.

Nishikori became the first Japanese man into the Australian quarter-finals in 80 years when he upset the French sixth seed, 2-6, 6-2, 6-1, 3-6, 6-3 in scorching conditions to earn a place in the last eight.

Murray, the British fourth seed, was on court for only 49 minutes before his Kazakh opponent Mikhail Kukushkin retired early in the third set with a hip flexor injury.

Murray said he was looking to hit the practice courts to retain his sharpness ahead of Wednesday's quarter-final after Kukushkin pulled out while trailing 6-1, 6-1, 1-0.

Nishikori became the first Japanese man to reach the last eight at the Australian Open since 1932. It is his best result at a grand slam, surpassing his fourth-round appearance at the 2008 US Open.

He also became only the second Japanese man to reach a grand slam quarter-final in the open era since Shuzo Matsuoka at Wimbledon in 1995.

"I was just playing one point at a time and it was not easy conditions today, Jo-Wilfried was playing well and I was just trying my best," Nishikori said.

"Hopefully it's big news in Japan. A lot of people have messaged me since my last win, so now it's a quarter-final and I'm really excited."

Nishikori broke Tsonga's serve six times and cashed in on the Frenchman's 70 unforced errors, 40 of them on his big forehand.

His only ace in the match brought up three match points in the final game and he clinched victory with a running volley at the net. Tsonga said Nishikori proved a difficult opponent in the heat.

"When you have a guy in front of you who returns everything, even when you serve at 215 (kilometres per hour, 134 miles an hour), it puts lot of pressure on you," he said.

"It's tough to play against him because he runs a lot and everything's coming back."

Meanwhile, Murray admitted he was bored by his one-sided match with struggling Kukushkin.

"Yeah, it's just boring. There was nothing happening on the court," Murray said of the match against his 92nd-ranked opponent.

"I didn't have to do anything. Just hitting the ball in the court and he wasn't running. He was making mistakes the first or second ball of the rally," said Murray, who also said was little excitement from the crowd.

Murray, a beaten finalist in the past two Australian Opens, said while he was happy to conserve energy in the sapping heat, he needed to put in some work to prepare for tougher matches ahead.

"It's perfect because you conserve energy. You just need to make sure, you know, today and tomorrow you hit enough balls to make sure you don't lose any rhythm.

"Because there were no rallies out there, I need to make sure I move around a little bit so I don't stiffen up in any way.

"But you can't look at it as a negative. At this stage of the tournament to be off the court in 45 minutes or so isn't bad."