Tennis:Top seed Maria Sharapova was in less than sparkling form as she ousted fellow Russian Anna Chakvetadze but nevertheless set up a semi final encounter with Kim Clijsters who overcame 62 unforced errors to down sixth seed Martina Hingis.
In an error-strewn match that lasted two hours and 13 minutes, Sharapova, 19, made 41 unforced errors and had her serve broken four times before eventually prevailing 7-6 (7-5) 7-5.
The opening set saw four breaks of serve and 11 of 12 points in the tie-break going against the server before Sharapova finally prevailed 7-5 in the tie-breaker .
After Chakvetadze had taken a medical time-out for treatment on her right shoulder between sets, the second set followed a similar pattern as the first with both players continuing to make mistakes and squander service games.
Leading 5-4, Sharapova wasted one match point on her opponent's serve but closed Chakvetadze out two games later to win the match with her fifth service break.
Sharapova said she was satisfied with her performance.
"I was just very competitive. Against a girl like that, that gets a lot of balls back, it's just a matter of who can be a little bit smarter, who can get an extra ball back, who is a little tougher," she said.
"I thought I did the job really well today. Overall I thought it was a bit scratchy. First set I was down a break, (but) I get back in the groove."
In Clijster's case the Belgian prevailed 3-6 6-4 6-3 in a three-set thriller. Playing in what is likely her final Australian Open, Clijsters broke the Swiss in the second game of the match only to see her own serve broken three times in the opening set as she went down 6-3 to the three-time champion.
The Belgian, who plans to retire at the end of this season, regained her composure in the second set, breaking Hingis twice to take a 5-2 lead before securing the set with a fine cross-court winner.
Both players had a break each early in the final set before Clijsters grabbed a crucial edge with another break in the seventh game to take a 4-3 lead.
Appropriately she closed out the match with another break of service, keeping her in contention for her first Australian Open title.
Despite falling in the quarter-finals for the second consecutive year, Hingis said after the match that she was pleased with how she played.
"I had the best chances today to beat her from all the matches we've played in the past," she said.
"Confidence-wise she definitely had the edge. But this time I definitely stepped it up. In the beginning we both were very nervous.
"But I came out stronger and I had my chances today.
"It was definitely disappointing. I felt like I was winning the match and I had all the things in my hands. But she's a great fighter. It was a great match."
Clijsters admitted she was still trying to work out how she won the match.
"I think the only two things that I did well today was that I fought and I tried," she said. "I think those are the two things that made me play a little bit better when I had to, when it was most important.
"That's the only thing you can do when you're not hitting the ball well and you feel like whatever you're trying is not really going your way.
"That's the only thing you can do. Hopefully (it) turns it around. Luckily for me, it did."