Top seed Roger Federer survived a five-set scare from unseeded German Tommy Haas on Monday to reach the quarter-finals of the Australian Open.
At two sets up the world number one's game inexplicably fell apart before he regained his composure to win 6-4, 6-0, 3-6, 4-6, 6-2.
Federer looked to be cruising to his fourth consecutive straight-sets win when he ripped through the first two sets in an hour before Haas staged a remarkable fightback to force the match into a fifth set.
Federer got the vital break in the sixth game when his German opponent missed an easy volley and broke again in the eighth game to advance to the quarter-finals.
He will play Russian fifth seed Nikolay Davydenko, who beat Slovakian ironman Dominik Hrbaty 4-6, 4-6, 6-4, 6-2, 6-3.
