Venue: Melbourne Park Date: 19 January-1 February
Coverage: BBC Red Button, BBC One & Two (including all Andy Murray matches), Radio 5 Live sports extra, BBC Sport website (Red Button coverage streamed on website throughout fortnight)
Saturday: Murray v Melzer live on BBC2 (streamed on website for UK users only) and BBC 5 Live sports extra from 0830 GMT
Ivanovic has been struggling for form since the middle of last season
Ana Ivanovic's poor form continued as she was beaten by Alisa Kleybanova in the Australian Open third round.
Fifth seed Ivanovic, who reached the final last year, dropped serve nine times and made 50 unforced errors on route to a 5-7 7-6 (7-5) 2-6 loss.
The Serb, 21, has won just one title since picking up her first Grand Slam trophy at the French Open in June.
World number one Jelena Jankovic is through to the last 16, as are Dinara Safina and a resurgent Jelena Dokic.
Dokic spent nearly three years away from the sport's top level and, after playing under the Serbian flag for a period, is now back under Tennis Australia's wing.
The 25-year-old was given raucous support by a packed Rod Laver Arena crowd as she roared back for a 3-6 6-1 6-2 win over 11th seed Caroline Wozniacki.
"I tried not to think about victory until I had match point," said Dokic afterwards. "That got me through the last game."
"I'm sorry for being a pain," she told the crowd, who cheered her wildly throughout. "I know I've been difficult at times and I want to apologise for that."
Dokic's surprise win over a player ranked 175 places above her in the rankings was quickly followed by Kleybanova's victory over Ivanovic.
Serbian Ivanovic has struggled for form, particularly with her serve, for the last six months and showed no signs of cohesion.
The French Open champion got off to a decent start in the opening set but at 5-3 she somehow conspired to lose the next four games.
Still shell-shocked, she then found herself three games down in the second set but fought back to steal it on a tie-break.
This was only a minor highlight for the 21-year-old to savour though as the free-hitting Kleybanova broke early on in the deciding set and sealed victory to set up a clash with Dokic in the fourth round.
"We both played great tennis and I really enjoyed the crowd over three sets," said Kleybanova. "I'm happy to win because I was able to play my best tennis today."
Ivanovic described her latest early defeat at a Grand Slam as "definitely a tough one".
She added: "It might sting at first. In the long run, I hope it makes me tougher."
Ivanovic's fellow Serb Jankovic suffered no such problems as she eased past Japan's Ai Sugiyama 6-4 6-4.
Jankovic was made to work hard for her victory by Sugiyama
Jankovic will now face Marion Bartoli in round four.
Bartoli, the 16th seed, looked in serious trouble when she lost the first set of her match against Lucie Safarova.
But the 2007 Wimbledon finalist launched an impressive fightback to come through 3-6 6-2 6-1.
Safina, who had never been past the second round at Melbourne Park, wrapped up her 6-2 6-2 victory over 25th seed Kaia Kanepi in one hour and six minutes.
Next up for the Russian is 15th seed Alize Cornet of France after she beat Slovakia's Daniela Hantuchova 4-5 6-4 6-2.
Finally I played my game and, compared to my first two matches, I reached my level
Safina struggled through her opening two matches but hit top form to beat Kanepi and lay down a marker for the rest of the tournament.
If she wins the Australian Open she will replace Jankovic as world number one.
"Finally I played my game and, compared to my first two matches, I reached my level," said Safina.
"From now I have to play like this or even better every day because there will be tougher and tougher openings coming up, but I'm really happy that I won in two sets."
Nadia Petrova became the first woman to reach the fourth round when Galina Voskoboeva of Kazakhstan retired with a back injury at 6-1 0-0 in the Russian's favour.
Petrova, seeded 10, will play compatriot and seventh seed Vera Zvonareva, who looked in top form as she swept to a 6-4 6-1 win against Italy's Sara Errani.
In the women's doubles, British number one Anne Keothavong and her partner Mervana Jugic-Salkic went down 6-1 6-2 to seventh seeds Maria Kirilenko and Flavia Pennetta in round two.