Andy Murray flies into Australian Open quarter-finals

Andy Murray took just 49 minutes to progress (GETTY IMAGES)

Even Andy Murray described his fourth-round victory here in the Australian Open today as "just boring". With Mikhail Kukushkin struggling to move because of a hip muscle problem following marathon five-set matches in the previous two rounds, Murray secured his passage in just 48 minutes as his Kazakh opponent retired when trailing 6-1, 6-1, 1-0.

Murray's quarter-final on Wednesday, however, should be anything but tedious. Kei Nishikori, who beat Jo-Wilfried Tsonga to become the first Japanese man to reach the last eight here for 80 years, is one of the sport's most exciting young talents. The 22-year-old graduate from Nick Bollettieri's Florida academy, where he went at the age of 14 despite not being able to speak a word of English, is a fine athlete and spectacular shot-maker.

Nishikori has become the highest ranked Japanese player in the Open era. The world No 26 is also the first man from his country to reach a Grand Slam quarter-final since Shuzo Matsuoka, who played in the last eight at Wimbledon in 1995.

"Kei is playing really, really well," Murray said, having watched some of Nishikori's 2-6, 6-2, 6-1, 3-6, 6-3 victory over Tsonga, the world No 6. "I've practised with him a few times. He's very good, very deceptive. For somebody that's not the tallest guy, he creates a lot of power from the back of the court.

"He deals with pace well, he can slice, he moves well. He was hitting a lot of winners out there. He was dictating all the points from the back of the court, which is difficult against someone like Tsonga. He's won a few long matches here."

Murray beat Nishikori for the loss of only three games in their only meeting three months ago in Shanghai, when the Japanese reached his first Masters Series semi-final. In his next tournament in Basle he beat Novak Djokovic before losing to Federer in the final.

Nishikori, who was helped on a consultancy basis last year by Murray's former coach, Brad Gilbert, won the only title of his career at Delray Beach in 2008, but it has been only in the last year that he has started to realise his potential. Because of an elbow injury he missed a large part of the 2009 and 2010 seasons, after which he dropped out of the world rankings completely. He won four Challenger tournaments in succession on his return and has been climbing steadily up the rankings ever since.

At 5ft 10 in and less than 11st, he is not the strongest of players, but proved with his victory today, on a scorching afternoon with temperatures reaching 34C, that he has improved his resilience. "I've seen him in the gym a lot," Murray said. "I think he's got in better shape."

Tsonga said: "When you have a guy in front of you who returns everything, even when you serve 215 [kph], it puts a lot of pressure [on you]. It's tough to play against him because he runs a lot and everything's coming back."

Fitness is rarely a problem for Murray, who went out to the practice courts later in the day after the premature end to his match against Kukushkin. The world No 92 took Murray to three sets in the Scot's first match of the year in Brisbane, but from the start it was clear that his movement was hampered.

"It was just boring - there was nothing happening on the court," Murray said. "I didn't have to do anything. I was just hitting the ball in the court and he wasn't running. He was making mistakes the first or second ball of the rally."

Not that Murray was complaining. "It's perfect because you conserve energy," he said after reaching the quarter-finals for the ninth time in his last 12 Grand Slam tournaments. "You just need to make sure, today and tomorrow, that 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."

The winner of Murray's quarter-final will then play either Djokovic or David Ferrer in the semi-finals. Djokovic, who beat Murray in the final last year, had dropped only 10 games in his first three matches and appeared to be coasting to victory over Lleyton Hewitt before the Australian staged a courageous fightback from two sets and 3-0 down.

At that stage the match was stopped briefly when a flock of birds flew into the stadium, after which Hewitt staged a remarkable recovery before eventually losing 6-1, 6-3, 4-6, 6-3. The world No 181's defeat left Murray as the only player from one of the Grand Slam host nations - Britain, France, Australia and the United States - through to the quarter-finals in either the men's or women's singles.