Hello and welcome to our live coverage of the second of today's women's quarter-finals at the Australian Open between world number one Caroline Wozniacki and defending champion Kim Clijsters.

Clijsters will now meet Victoria Azarenka in the semi-finals... for Wozniacki, the wait for a Grand Slam title goes on.

WOZNIACKI 3-6 6-7(4) - GAME, SET & MATCH - Wozniacki delivers a great serve out wide before moving to the net and volleying home to go 2-1 ahead before Clijsters sends down an ace in response. A backhand winner from Wozniacki draws gasps of appreciation from the crowd before Clijsters hits back with a backhand at the net. And then the Belgian brings up two match points with a stunning forehand winner. She takes it! Amazing from the defending champ!

WOZNIACKI 3-6 6-6 - TIE-BREAK - Kim hits the net on the opening point, and Wozniacki clenches her fist in celebration. This is huge, this game. But she has an aberration soon after as she fires wide and then again a point later, but Clijsters is also playing tight and making unforced errors. Kim goes wide and Wozniacki sends this set into a tie-breaker!

WOZNIACKI 3-6 5-6 - Clijsters comes through this one, sealing the game with a stunning backhand winner! The pressure is intensifying on Rod Laver Arena as Wozniacki now has to serve to stay in the match.

WOZNIACKI 3-6 5-5 - What a backhand from Kim as she kicks off this game with a bang. But two poor unforced errors later she finds herself with a mountain to climb. Another wayward return brings groans from the crowd as Wozniacki holds serve to level at 5-5!

WOZNIACKI 3-6 4-5 - BREAK - Kim is off the mark on the first two points but she responds on the third point with a sizzling forehand that Wozniacki can only return out. And then she moves to the net with purpose to volley home and level at 30-30. But she cannot maintain that intensity and Wozniacki breaks back to give herself a chance to level the second set at five games all. There's still legs in this one!

WOZNIACKI 3-6 3-5 - Well done Caroline! The reigning world number one hangs in there with a solid service game to heap the pressure on Clijsters, who now has to hold serve to make the semi-finals.

WOZNIACKI 3-6 2-5 - Make that one game away from another semi-final. Kimmy holds serve to 15 and if she can clinch victory today, it will mark her sixth career win over a world number one. Although Wozniacki may not hold that title much longer if she loses here.

WOZNIACKI 3-6 2-4 - BREAK - Clijsters responds brilliantly as some brilliant retrieval work sees her bring up three break points of her own. She goes long on the first, a net cord does her no favours on the second but on the third a whipped forehand beats Wozniacki and Clijsters has another break. She's just two games away from a semi-final meeting with Victoria Azarenka now.

WOZNIACKI 3-6 2-3 - BREAK - Kim's power is incredible on the first point, but she changes it up with a drop shot that unfortunately doesn't come off. She doesn't recover and Wozniacki storms to three break point opportunities... the world number one wastes no time in claiming the first one to get things back onto serve in this second set!

WOZNIACKI 3-6 1-3 - BREAK - Wozniacki finds herself facing break point after a wayward shot from the baseline but she saves it with an ace. Kim comes again though as a backhand return beats the Dane all ends up. And she claims the break to open up a two-game lead! Wozniacki has it all to do now.

WOZNIACKI 3-6 1-2 - Emphatic is the word as Clijsters holds serve to love to take the lead once again. Since her return to tennis as a mother, she is 18-4 against top 10 players, including two wins over Wozniacki.

WOZNIACKI 3-6 1-1 - Wozniacki responds well to the pressure and holds serve. The last time the top seed lost here as early as the quarter-final was Justine Henin in 2008.

WOZNIACKI 3-6 0-1 - Clijsters starts the second set as she ended the first - by winning the game. The Belgian is trying to become the eighth player to successfully defend her title at the Australian Open, after Court, Goolagong, Graf, Seles, Hingis, Capriati and Serena.

WOZNIACKI 3-6 - SET - Wozniacki has a chance to put this game to bed, but she allows Kim back into the point and the defending champ fires a forehand winner to level at 30-30. Kim surges forward and Wozniacki is forced to save three set points before Kim's pressure finally tells, firing a forehand volley over the net! She lets out a whoop and Aussie Kim is looking good a set up!

WOZNIACKI 3-5 - BREAK - At 30-30, Kim produces a third ace of the match to bring up set point, which she wastes as she goes long. She then sees her normally trustworthy forehand hit the net and all of a sudden Wozniacki has break point! And the Dane capitalises as Clijsters goes long again! Perhaps this set isn't over quite yet...

WOZNIACKI 2-5 - BREAK - Clijsters, of course, had that scare during her incredible win over Li Na the other day, but she's showing no signs of discomfort today. A monstrous backhand winner down the line brings up two break points and she claims it on the next point after some big hitting from the baseline, albeit thanks to a lucky net cord!

WOZNIACKI 2-4 - Clijsters whips that forehand of hers once again to get things going this game and she never looks back. It's a double-quick hold of serve for the defending champion and crowd favourite, who has a perfect 6-0 record in quarter-finals at the Australian Open.

WOZNIACKI 2-3 - Clijsters's forehand again delivers a winner as the Belgian draws level at 30-0 but a shot into the net later gives Wozniacki the chance to hold. She does so, with an ace! The Dane, of course, is still looking to break her Grand Slam duck, but she is bidding to make her fifth GS semi today.

The winner of this match will play Victoria Azarenka, who was made to sweat in the blistering heat but eventually overcame Aggie Radwanska in three sets earlier today.