The former world number one Amelie Mauresmo was dumped out by the unheralded Australian Casey Dellacqua in a three-set stunner. Dellacqua used the backing of a capacity Rod Laver Arena to down the 2006 champion 3-6, 6-4, 6-4 in just over two hours.

Mauresmo, who slumped out of the world top 10 on the back of an interrupted 2007 season, struggled on her serve and endured 10 double faults, including six in the second set and three in the decider.

The Frenchwoman broke Dellacqua, ranked 78 in the world, midway through the third set to lock the game away at 3-3 and seemed destined to down her less experienced 22-year-old opponent.

However, 18th seed Mauresmo struck trouble on serve and immediately handed the break back.

Unsettled by another double fault in the 10th game, a frustrated Mauresmo then watched helplessly as a booming Dellacqua forehand flashed by her to signal the end of her resistance.

Dellacqua - who had not been past the first round in her five previous attempts at Melbourne Park - moves on to a fourth-round meeting with the Serbian third seed Jelena Jankovic.

Despite her double-fault dramas, Mauresmo still felt she had the opportunities to win the match.

"I definitely thought I had some in the second and third sets, but wasn't able to take those," Mauresmo said.

"That's the area of the game I should have done better and been more aggressive in these moments. That's where I'm a little bit frustrated and disappointed."

An emotional Dellacqua wiped away tears as the 18,000-strong crowd cheered her off the court.

"It means so much," she said after a win which ensures she will end the tournament as her nation's top-ranked female player. "Since I was a young girl, you just dream of playing matches like that. I settled really well. I just felt like I had nothing to lose."

While Dellacqua was riding high, Jelena Jankovic had turned to ice baths in a bid to recover for their next-round match. The Serbian's quest for her maiden Grand Slam title has been a frustrating and fatiguing one to date.

Yesterday she overcame yet another epic encounter and even a warning for receiving coaching from the stands to advance to the fourth round.

The top half of the women's draw is heading for a series of thrilling matches next week as third seed Jankovic, top seed Justine Henin, defending champion Serena Williams and last year's beaten finalist Maria Sharapova all reached the fourth round.

And they were joined there by the highly rated 11th and 12th seeds, Russian Elena Dementieva and Czech Nicole Vaidisova, to add to the excitement.

The odd player out in the top half of the draw is certainly the Taiwan qualifier Su-Wei Hsieh, who set up a dream fourth-round meeting with Henin after a 6-2, 6-7 (3-7), 6-4 win over France's Aravane Rezai.

The 22-year-old is playing in her first Australian Open after having failed to qualify in 2002, 2006 and 2007.

Jankovic again felt the pinch as she eventually downed France's number-30 seed, Virginie Razzano, 6-2, 4-6, 6-1 on Rod Laver Arena.

The two-hour battle - played in the hottest time of what was the warmest day of the Open so far - followed on from Jankovic's epic first-round win over Austria's Tamira Paszek, which she clinched 12-10 in the third set.

Jankovic admitted afterwards her fitness levels "were not that great actually".

"I wish I could have finished that match in two sets," she said.

"I got very tired and you probably could have seen that during the match with my attitude because my head was down and I was just kind of dragging myself around the court."

Jankovic also had to deal with a warning from the umpire for receiving coaching from her mother in the stands - a charge she emphatically denied post-match.

"I think that was wrong because my mum is just supporting over there in my box," she added.

Meanwhile, Henin took her winning streak - which began following Wimbledon last year - to 31 after beating the Italian number 25 seed, Francesca Schiavone, 7-5, 6-4.

Williams, aiming for a fourth success at Melbourne Park, downed the Belarusian number-26 seed, Victoria Azarenka by the same score, serving 15 aces along the way.