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. Highlights on BBC1 at 1300 GMT
Federer is still on course for a semi-final meeting with Djokovic
Roger Federer hit top form to secure victory over fellow former champion Marat Safin in an entertaining Australian Open third-round clash.
The world number two beat Safin 6-3 6-2 7-6 (7-5) to set up a fourth-round clash with Tomas Berdych.
Defending champion Novak Djokovic was given a stern test by Amer Delic before winning 6-2 4-6 6-3 7-6 (7-4) to book a meeting with Marcos Baghdatis.
Seventh seed Andy Roddick is through to face Tommy Robredo.
Federer, seeking a record-equalling 14th Grand Slam win in Melbourne, quickly took charge against Safin.
The opening set was over in 26 minutes as Safin's serve was broken in the eighth game.
The Russian, who won the tournament in 2005 having beaten Federer in the semi-final, hit a number of big serves in the second set but was undone by breaks in the fifth and seventh games.
I thought Marat started to play really well towards the end so I'm happy I got through
Whilst Safin utilised his powerful serve and some expertly played lob-shots to good effect at times, his forehand play was not up to the standards needed to compete against such a strong opponent.
In contrast, Federer was the epitome of consistency and played some superb passing shots to win key points throughout.
The final set went to a tie-break and despite throwing away a 4-1 lead Federer served an ace at 5-5 to tip things in his favour.
"It's special to play Marat, we go way back," said Federer afterwards. "I think we like playing each other. It doesn't matter who wins, it is always a good contest."
Afterwards Safin confirmed he is likely to retire this year, bringing to an end a career that includes two Grand Slam victories.
"I don't like this bye-bye part," he said. "It's just a sad story. It's not for me. I prefer to leave this way, quietly, nice, with a great match."
Djokovic was made to work much harder than expected against Delic, a Bosnia-born American who entered the main draw as a lucky loser.
And he could be in for a tougher time in his last 16-match against fit-again 2006 finalist Baghdatis, who trounced American Mardy Fish 6-2 6-4 6-4.
Delic seemed nervous and struggled to find any sort of consistency in the first set, which Djokovic wrapped up in 32 minutes.
But with vocal sections of the crowd on his side, Delic began to relax, the winners started to flow and the second set followed.
Djokovic was pushed all the way by lucky loser entry Delic
Despite not playing his best tennis, Djokovic gained the single break required to snatch the third set but Delic hit form in the fourth.
The world number 127 took his ace tally for the match to 16, and to the tournament to 70, before going 40-15 up on the Djokovic serve at 5-4 ahead.
But the Serb world number three kept his cool to hold and then assert his authority in the tie-break.
"It was a great battle. I look on the positive side - I played a tough match, which is good for my game and my rhythm," said Djokovic.
"I tried to finish it off in straight sets but he was serving well and I couldn't get my rhythm.
"He was serving at over 210 km per hour in the fourth set but I knew I had to stay with him, stay focused and take my chances in the tie-break.
"I tried not to think about a fifth set and I'm very happy to get through.
It's always good to play here - there is a big Croatian community and I hope they will be here for my next match
Before the match, Delic had appealed for Serbian and Bosnian fans not to disrupt his match against Djokovic - and the supporters were well-behaved during the action.
But afterwards, police arrested two men and ejected another 30 people from the grounds after rival fans began throwing chairs and trading punches and kicks.
On the court, Roddick was in ruthless form as he brought Fabrice Santoro's last Australian Open appearance to an end with a 6-3 6-4 6-2 win.
The 36-year-old Frenchman, who was the oldest man in the main draw, has said that 2009 would be his final year on the ATP tour.
Roddick will meet Robredo in the fourth round after the Spaniard comfortably beat David Nalbandian's conqueror Lu Yen-hsun 6-1 6-3 6-2.
Eighth seed Juan Martin del Potro produced another impressive display to see off Luxembourg's Gilles Muller in four sets.
Muller hardly put a foot wrong in the first set, which he took on a tie-break, but Del Potro's class shone through thereafter.
The Argentine took confidence from claiming the second set, reversed a break to power through the third and gained a decisive break a 5-5 before serving out the fourth for a 6-7 (5-7) 7-5 6-3 7-5 victory.
In the fourth round Del Potro plays Marin Cilic after the number 19 seed claimed a 7-6 (7-5) 6-3 6-4 victory over Spain's David Ferrer, seeded 11.
The 20-year-old Croat has now reached the fourth round in three of his six appearances at Melbourne Park and is in tremendous form.
"I moved and served very well today, which I'm really pleased about," said Cilic. "I had to mix up my game and it worked.
"It's always good to play here - there is a big Croatian community and I hope they will be here for my next match."
In the doubles, Britain's Ross Hutchins and his partner Stephen Huss were knocked out in the second by Mariusz Fyrstenberg and Marcin Matkowski, the sixth seeds from Poland.