World No. 1 Caroline Wozniacki roared out of the blocks against Jelena Jankovic on Sunday but ultimately stumbled across the finishing line to reach the Australian Open quarter-finals.

33949 - Wozniacki limps past Jankovic to book Clijsters clash

Wozniacki has undoubtedly been the most consistent player in the female game for at least the past 12 months, as reflected by her world ranking, but rarely has she even suggested on court that a major title could be set to arrive. That was the case again as she choked badly in a 6-0 7-5 triumph over former world No. 1 Jankovic.

The Dane has previously been accused of relying on her defensive capabilities - which are excellent - to get her to a certain stage in competitions. Against Jankovic there were glimpses of aggression as she turned defence into attack on several occasions, but when it came to serving for the match at 5-2 and 5-4, she caved on both occasions.

Jankovic's first-set nightmare was largely all of her own making. In 34 minutes she delivered 18 unforced errors to gift Wozniacki three breaks en route to a whitewash.

The Serbian player finally got on the board in the second, but just when any thoughts of a comeback threatened, Wozniacki produced one of the shots of the tournament. Chasing down a backhand deep behind the baseline, Wozniacki clipped the ball down the line - back from where Jankovic had just come - completely wrong-footing her rival to turn the point on its head.

Two more breaks took Wozniacki to the cusp of victory in the second, but Jankovic hauled herself back from 5-1 to 5-5 with some outstanding hitting off her forehand side. The hard work done, Jankovic then allowed her own focus to slip as Wozniacki broke to serve for the match once again, finally closing it out at the third time of asking.

Defending champion Kim Clijsters is next for Wozniacki after the Belgian pulled off a stunning late comeback amid an injury scare to defeat Li Na 4-6 7-6(6) 6-4 in a repeat of the 2011 final. Clijsters badly rolled her left ankle early in the first set, immediately moving to her seat and calling for the trainer after limping from the court.

The 11th seed appeared out of sorts after receiving treatment on her injury, but fought on valiantly to take a lengthy second-set tiebreaker 8-6. The momentum was all Clijsters' from that moment on as she stormed to a 5-1 lead in the decisive set. However, Na found energy reserves of her own to force a nervy Clijsters to serve for the match twice before finally booking her place in the quarter-finals.

Third seed Victoria Azarenka took her unbeaten streak to nine matches with a straight-sets win over Iveta Benesova to book her place in the quarter-finals. Azarenka claimed a comfortable 6-2 6-2 victory over her Czech opponent.

The Belarusian has been in sizzling form since winning the Sydney International tournament last week, dropping just 11 games en route to the best Australian Open performance of her career.

Early breaks in both sets gave the world No. 3 the edge as Benesova appeared unable to withstand the force of Azarenka's groundstrokes. Benesova did show fight to save four match points before Azarenka booked her place in the final eight of the tournament.

She will now play eighth seed Agnieszka Radwanska who easily accounted for Germany's Julia Goerges 6-1 6-1. The Pole never looked troubled against Goerges, racing to an early 3-0 lead in the first set before the 22nd seed was able to eventually get on the scoreboard.

Radwanska went on with the thrashing to record a 54-minute victory in what was Goerges' first appearance in a grand slam round of 16.