MELBOURNE: Rafael Nadal set up a blockbuster Australian Open quarter-final with Andy Murray on Sunday and Justine Henin's comeback stayed on track, but there was misery for Dinara Safina who pulled out injured.

On a day of upsets, the tournament ended for US Open champion Juan Martin del Potro, French Open champion Svetlana Kuznetsova and Chilean 11th seed Fernando Gonzalez.

Second seed Safina limped out with a back problem during her fourth round clash with unseeded countrywoman Maria Kirilenko.

The 23-year-old Russian, the runner-up last year, battled the injury in late 2009 and withdrew from the Brisbane International this month.

She was trailing 4-5 and 30-40 when she walked towards the umpire and indicated her night was over.

"My back again. It suddenly hit me, it was getting worse and worse," said Safina, clearly in pain.

"I have no idea really how it could happen. It's really, really terrible."

Zheng Jie, meanwhile, rewrote the history books by becoming the first Chinese player to reach the last eight in Melbourne and will now play Kirilenko.

Spain's second seeded Nadal was put to the test by big-serving Croat Ivo Karlovic, who slammed down 28 aces, before he muted the challenge 6-4, 4-6, 6-4, 6-4.

It ensured an enticing last eight showdown with in-form fifth seed Murray after the Scot tamed another big-server, American John Isner, 7-6 (7/4), 6-3, 6-2.

"Murray is one of the more dangerous players on the tour, he can play aggressively and defensively," said Nadal, who has not won a tournament in eight months after being hampered by injury.

"I will have to play as well as I can and use my forehand."

Murray will be competing in his first Australian quarter-final and is the first Briton since John Lloyd in 1985 to get this far.

He showcased his exciting strokeplay against Isner and has yet to drop a set.

"I'm playing well. No question about that," said Murray, who lost to Nadal in five sets in the fourth round of the 2007 Australian Open.

"I just need to play like I have been and maybe a bit more if I want to win the tournament."

The pair have played each other nine times with Nadal winning seven.

Henin's successful return to tennis after an 18-month retirement continued full steam when the seven-time Grand Slam champion beat fellow Belgian and world number 16 Yanina Wickmayer 7-6 (7/3), 1-6, 6-3.

"It's a great feeling to be back, everything is going so well," said Henin, who is at her first Grand Slam since the Australian Open in 2008 after being handed a wildcard by organisers.

"Physically, it's tough as I didn't play for two years, but I love being back on court."

Her victory matched the best performance by a wildcard here in the Open Era -- Martina Hingis in 2006 and Jelena Dokic in 2009 also made the quarters -- and earned her a crack at Russian Nadia Petrova for a place in the semi-finals.

Petrova, the 19th seed, made the last eight by beating third seed Kuznetsova, continuing her giantkilling ways having already ousted Kim Clijsters.

She won 6-3, 3-6, 6-1 and Kuznetsova admitted she deserved to lose.

"I was struggling a little bit, I was not good today. I think I deserved to lose," he said.

Zheng's achievement was impressive, with the unseeded 26-year-old upsetting Ukrainian 31st seed Alona Bondarenko 7-6 (7/5), 6-4 as she and Li Na, who plays her fourth round match on Monday, continue to fly the flag for China.

Zheng proved to be marginally steadier than the Ukrainian in a match where both women struggled to hold their serves.

Argentina's del Potro crashed out of contention in a five-set epic with 14th seed Marin Cilic.

The Croatian outlasted an exhausted del Potro 5-7, 6-4, 7-5, 5-7, 6-3 to earn himself a quarter-final against American seventh seed Andy Roddick who battled back to beat Gonzalez 6-3, 3-6, 4-6, 7-5, 6-2.