Former champion Amelie Mauresmo suffered her earliest Australian Open defeat since 2000 when she was upended 3-6, 6-4, 6-4 by unseeded Australian Casey Dellacqua in the third round on Friday.

The Frenchwoman, who slipped down the rankings to 18th at the end of last year, led by a break of serve in the final set but Dellacqua hit back to clinch the biggest victory of her career.

Melbourne Park stays fertile for seeds | Images

"I am shaking so much, I am so excited," the 22-year-old Dellacqua said in a courtside interview.

World number 78 Dellacqua, who had only ever won one Grand Slam match before this year, next plays third seed Jelena Jankovic.

"I have nothing to lose, I'm just going to go for it," Dellacqua said.

Jankovic shrugged off nagging injuries and was spoken to by the umpire for receiving coaching to record a 6-2, 4-6, 6-1 victory over Virginie Razzano of France [Images].

The Serb had struggled through her opening two matches, saving three match points against Tamira Paszek in the first round, and the clash with Razzano was no different.

"I have no idea what it is," a perplexed Jankovic told reporters. "I should have finished in two sets, but I completely lost my concentration (at the) end of the second.

"I also got very tired and I wasn't thinking about what I had to do in order to win."

The world number four had raced through the first set but allowed the French baseliner back into the match with sloppy errors.

"I wish I could have finished that match in two sets. I got very tired, and you probably could have seen that during my match with my attitude," the 22-year-old added.

"My head was down and I just was kind of dragging myself around the court."

Jankovic was also upset that chair umpire Mariana Alves accused her of receiving coaching advice from her mother in the players' box.

Jankovic said her mum had only been offering encouragement in her native Serbian and had not given any advice.

"I think it was wrong because my mum ... is just supporting over there in my box ... she was not coaching me," said Jankovic.

"She was just trying to tell me like 'c'mon, keep going'. She was just trying to lift me up a bit.

"She wasn't telling me, 'hit to her forehand; go to the net; keep your left hand up when you serve', or something. She wasn't doing that."

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