Top seed Roger Federer survived a testing examination from Russian fifth seed Nikolay Davydenko before winning 6-4, 3-6, 7-6, 7-6 to reach the Australian Open semi-finals on Wednesday.
The world number one was pushed all the way by Davydenko but his sublime skills and unrivalled ability to raise his game when it matters enabled the Swiss master to book his place in the last four against German Nicolas Kiefer.
Federer was pushed to five sets in his fourth round match with Tommy Haas and it briefly looked as though he might have to go the full distance again after the Russian pinched the second set and served for the third.
But Federer broke back when he needed to and then saved six set points before taking the third set in a tiebreak and then won the fourth in another tiebreak to remain on course for his second Australian Open crown.