World No.2 Dinara Safina caused a sensation at the Australian Open on Sunday night by retiring midway through her fourth-round match against fellow Russian Maria Kirilenko with a reoccurrence of a lower back injury.
Safina, who was thrashed in last year's decider by Serena Williams, grimaced with pain as she was trailing 4-5 and 30-40 before calling it quits.
Safina was forced to sit out the last two months of the season after first suffering the injury at the WTA Championships last October.
She also withdrew from the first tournament this year - the Brisbane International - claiming she needed further treatment on her back.
Safina took painkillers before the match and again after taking a 3-2 lead but was forced to pull out a short time later.
"It suddenly hit me. It was getting worse and worse, I have no idea really how it could happen, it's really, really terrible," she said afterwards.
"Today I warm up, it was fine. I was cooling down and I start to feel a little more pain. Suddenly I played a long game at 3-2. I won the game. I turned to my coach and said 'I cannot move anymore'."
Safina had looked in good form so far at Melbourne Park, cruising through her opening three rounds without dropping a set.
She was bidding to break her Grand Slam duck after three runner-up finishes at the French Open in 2008 and 2009, and last year's Australian Open.
Safina's withdrawal was good news for world No.58 Kirilenko, who advanced to her first Grand Slam quarter-final.
Kirilenko, who ousted 2008 champion Maria Sharapova in the first round, will take on China's Zheng Jie for a place in the last four.
"I'm happy about it. But I prefer, you know, to win and get - like to win all match and get to the quarter-final than to win like this," she said.
Meanwhile, former world No.1 Justine Henin's dream run continued after advancing to the quarter-finals with a three-set win over Belgian compatriot Yanina Wickmayer
The seven-time Grand Slam champion, on the comeback trail after 19 months out of the game, displayed her trademark grit to grind out a 7-6 (7-3) 1-6 6-3 win in two hours and 13 minutes.
Wickmayer, making her own return to tennis after being banned for breaching anti-doping regulations, squandered three set points at 5-3 in the first set to allow Henin back into the contest, before the 27-year-old seized control of the tie-breaker.
Wickmayer lifted her performance in the second set but Henin somehow found something extra to break her younger opponent in the opening game of the third set and going on to seal a memorable win.
Wickmayer, the world No.16, was on an 11-match winning streak going into Sunday's match, including three matches she won in qualifying for the tournament.
The 20-year-old was suspended for 12 months last November under the World Anti-Doping Agency's 'whereabouts rule' which requires players inside the top 50 to report where they are. The suspension was later overturned on appeal.
Wickmayer accepted a wildcard into the season-opening ASB Classic in Auckland - a tournament she went on to win - but was forced to qualify for this year's Australian Open after missing the deadline for the main draw.
"I'm disappointed. I had my chances in the first set. But, I mean, it's a great experience for me and I'm really