Roddick survives marathon encounter with Ancic

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

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.

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.