Roddick and Federer through

Andy Roddick won through to the quarter-finals of the Australian Open after a rollercoaster match against Croatian Mario Ancic on day seven.

Andy Roddick won through to the quarter-finals on day seven of the Australian Open after a rollercoaster match against Croatian Mario Ancic.

Roger Federer also cleared his fourth-round hurdle when he cruised past Novak Djokovic, with seventh seed Tommy Robredo, Czech Tomas Berdych and German 12th seed Tommy Haas the other winners today.

Roddick and Ancic traded sets in the 183-minute encounter with the American eventually taking the match 6-3 3-6 6-1 5-7 6-4.

It was Roddick's second epic in a row after the world number seven went to four sets, including two tiebreakers, against Marat Safin in his physical third-round encounter.

It has been well documented that Roddick has worked hard with new coach Jimmy Conners, and according to Roddick the former grand slam winner has been providing him with plenty of useful advice between matches.

"If you're already in a slam and something needs a major overhaul, I'm afraid it's a little bit too late," Roddick said.

"But (he has) definitely (been giving me) little hints here and there during a warm-up, during a day off."

Roddick has another tough task ahead in the quarters, where he will meet his old high-school friend Mardy Fish after the unseeded American continued his run through the tournament.

Fish knocked out fourth seed Ivan Ljubicic in his first-round clash and was handed a free ticket through the third round after Australian veteran, Wayne Arthurs, retired just three games into their match.

He went on to beat Spanish 16th seed David Ferrer today in the fourth round 6-1 7-6 (7-4) 2-6 7-5.

"I'd lost to him the last two times we played," Fish said. "We've played in some pretty big matches, but not like that."

Fish sent down 15 aces, but made a massive 53 unforced errors, which he will look to rectify against Roddick.

In the night session at Melbourne Park, exciting youngster Novak Djokovic was pitted against Federer and no matter what the Serb threw at the Swiss master, Federer returned it with interest.

The world number one took the match 6-2 7-5 6-3 and despite the one-sided scoreline, the two thrilled the crowd with their massive forehands and pin-point precision.

On Vodafone Arena, Robredo beat 20-year-old Frenchman Richard Gasquet 6-4 6-2 3-6 6-4 and earned the right to challenge Federer in the quarter-finals.

Robredo had no problem with Gasquet's serve and created 21 break-point opportunities, although he only managed to convert four of them.

The rain caused havoc on day six and meant that a number of matches had to be held over to today.

Tommy Haas finally began his match against compatriot Florian Mayer, 24 hours after the original scheduled time.

Haas was too strong for his opponent - who spent a large proportion of 2006 on the Challenger Circuit - and took the match in straight sets 7-6 (7-3) 6-3 6-3.

The number 12 seed has not dropped a set in his first three matches and hopes to be fresh for his fourth-round match against David Nalbandian, even though he does not have a day's rest between matches.

Just like his girlfriend, Lucie Safarova, Czech Tomas Berdych enjoyed a straight-sets win.

Berdych cruised past Russian Dmitry Tursunov 6-2 6-1 6-1, restricting his unforced error count to 17 while Tursunov whipped balls wide and into the net to finish with 36 unforced errors.

"I have to say that it was my best tennis so far in Melbourne," Berdych said after his match.

"Today everything was fine. From first point to the last one everything was good."