Elite trio exit Australian Open

The Australian Open claimed three high-profile victims yesterday as the demands of the first grand slam of the year left players battling exhaustion and agonising pain.

Dinara Safina suffered most. The Russian had to quit her fourth round match against Maria Kirilenko after her injured back flared up again, raising doubts about her immediate playing future.

"It's really, really terrible," she explained. "I cannot make any movement. Whatever I try to move, it hurts terribly."

Fatigue contributed to the surprise defeats of Argentina's US Open champion Juan Martin Del Potro and Svetlana Kuznetsova, the French Open champion. Both were able to finish their matches but their legs were heavy and their bodies weary.

"I will go home and I will see the doctors there," Del Potro said after his 5-7 6-4 7-5 5-7 6-3 loss to Croatia's Marin Cilic, an underrated player ranked 14th in the world.

Kuznetsova was beaten 6-3 3-6 6-1 by her fellow-Russian Nadia Petrova, who is quickly building a reputation as the tournament's giant-killer after slaughtering Kim Clijsters in her previous match.

She is the only seeded player left in the bottom half of the women's draw but plays Justine Henin in the next round after the former world number one beat her fellow-Belgian Yanina Wickmayer 7-6 1-6 6-3.

Henin is playing just her second tournament since coming out of retirement. She has retained the same killer instinct that enabled her to win seven grand slam titles but is concerned about the effects on her health.

"My left leg is quite sore. I sprained my ankle today also when I fell down," she said.

"Physically it hasn't been easy in the last few days."

Rafa Nadal and Andy Murray brought down a pair of giants to set up a tantalising quarter-final between two of the biggest names in men's tennis.

Nadal defeated Ivo Karlovic, a 2.08 metres tall Croatian whose serves come down like thunderbolts 6-4 4-6 6-4 6-4 while Murray beat the 2.06 metres John Isner 7-6 6-3 6-2.

Nadal's match against Karlovic was not one for the traditionalists, proving more like pistols at dawn than the genteel game once played at Victorian garden parties.

Karlovic rifled 28 aces past the Spaniard but the defending champion knows a thing or two about how to win. He remained patient, rolled the dice a few times and correctly guessed which way to go, then took his chances when they came.

Isner is shorter than Karlovic but his serve is no less lethal. The American had thumped down 81 aces in his first three matches and added 14 more against Murray.

The Scotsman is one of the best returners in the game and he showed why, frustrating Isner with his ability to get the ball back in play.

Unlike Karlovic, Isner does not rely just on his serve and volley and was happy to go behind the baseline and rally with Murray, who is yet to drop a set at Melbourne Park this year and brimming with confidence.

Kirilenko's joy at reaching her first grand slam quarter-final was tempered by her concern for her Russian compatriot.

Kirilenko, who upset Maria Sharapova in the opening round, said she was unaware that Safina was in excruciating pain because she was so focused on the match.

She was one point away from winning the first set when Safina hobbled to the net and said she was unable to continue.

"It's my first time in the quarter-final so, yeah I'm happy about it but I would have preferred to win the match than get to the quarter-finals like this."

Kirilenko's next opponent is China's Zheng Jie, who defeated Ukraine's Alona Bondarenko 7-6 6-4 while Cilic will face Andy Roddick who beat Fernando Gonzalez 6-3 3-6 4-6 7-5 6-2.