- Kei Nishikori becomes first Japanese man in 80 years to reach Australian Open last eight
- The 24th seed registers a shock win against French sixth seed Jo-Wilfried Tsonga
- He next plays fourth seed Andy Murray, who advances as Mikhail Kukushkin retires injured
- Top seed Novak Djokovic also through with win against Australia's Lleyton Hewitt
Kei Nishikori became the first Japanese male to reach the quarterfinals of the Australian Open since 1932 when he held on to earn a shock five-set win over sixth seed Jo-Wilfried Tsonga on Monday.
Nishikori, ranked 26th in the world, blew a two-set lead before beating the Frenchman for the second time in his career, triumphing 2-6 6-2 6-1 3-6 6-3 in three and a half hours.
The 22-year-old, who will next face world No. 4 Andy Murray, beat his previous best grand slam performance -- reaching the fourth round of the 2008 U.S. Open. He is the first Japanese male player to reach the last eight of one of the four majors since Shuzo Matsuoka at Wimbledon in 1995.
"This is the first quarterfinal for me," an exhausted Nishikori, told reporters after his second successive five-set match.
"I feel I'm stepping up. It was tough because he was still playing well in the fifth. I was having trouble with making returns. I started getting nervous ... But still I was playing aggressive on important points. I was making good serves. So that helped me to get the games."
Nishikori beat world No. 1 Novak Djokovic in the Basel semis in October before losing to Roger Federer, having learned a lesson in his thrashing by Murray in the last four in Shanghai in his preceding tournament.
"He kind of destroyed me. But I have no pressure now. He's one of the players I have to play like him. I learn a lot of things from him. It's going to be tough, but I try to do my best tennis."
Nishikori said he hoped he could inspire Asian men's players, as China's Li Na did for the region's women last year by reaching the Australian Open final and then winning the French Open.
"It's an honor to make a lot of histories, to be the No. 1 player in Japan. But that never gives me pressure," said Nishikori, who is a graduate of the Nick Bollettieri academy in Florida which has produced many top players such as Andre Agassi, the Williams sisters and Maria Sharapova..
"There's a lot of good players in Asia. But, yeah, I'm happy to get to the top from Asia, and hopefully I can be like Li Na for the men."
Fourth seed Murray, the runner-up in Melbourne for the last two years, was coasting 6-1 6-1 1-0 against Kazakhstan's Mikhail Kukushkin when the world No. 92 was forced to retire with a left hip flexor injury.
"I'll definitely be fresh for the next few rounds hopefully," said Murray, who has yet to win a first grand slam title despite reaching four finals. "I just need to make sure I do the right things the next couple days to get ready for the quarters."
Top seed and defending champion Novak Djokovic survived a spirited third-set fightback from former world No. 1 and home-crowd favorite Lleyton Hewitt to seal a 6-1 6-3 4-6 6-3 triumph in the late match.
Hewitt, granted a wildcard for the tournament after a long fitness struggle has seen him dropped to 181st in the rankings, showed glimpses of the form which took him to two grand slam titles.
But Djokovic -- a four-time grand slam winner including three major titles in 2011 -- eventually proved too strong and the Serbian world No. 1 eventually saw off the 30-year-old Hewitt in just under three hours in a match that went past 1 a.m. local time.
"I played some loose points and got him back into the match. But credit to him as well for being competitive, for not giving up," Djokovic said.
"This is something you can expect from Lleyton who is very well-known for his fighting spirit. He had the crowd, he had the big support. It got intense. Especially the start of the fourth set we had some great rallies."
Fifth seed David Ferrer awaits Djokovic in the next round after the Spaniard eased to a 6-4 6-4 6-1 victory against French No. 17 Richard Gasquet.
Seventh seed Tomas Berdych booked his place in the last eight with a four-set success against Spanish No. 10 Nicolas Almagro on Sunday, but the Czech was booed by the Hisense Arena crowd for refusing to shake his opponent's hand at the end of the match.
It followed an incident in the fourth set where Berdych accused Almagro of purposefully aiming a volley at his face, with the ball striking him on the arm.
"Whoever has played the tennis knows that the court is pretty big, and you always have some space to put the ball in," said Berdych told reporters.
"And not even if you stand each other like three or four meters close to the guy, just try to hit it straight to your face, you know. I was just able and lucky to somehow fell down.
"I already take it as a past, it's just one thing that what happened from the side of Nico ... So I think if they want to look at it like that, then I think maybe we both did some mistake."
Berdych's last-eight opponent will be 2009 champion Rafael Nadal, the second seed who beat fellow Spaniard Feliciano Lopez 6-4 6-4 6-2.