Federer survives Davydenko test

Top seed Roger Federer booked his place in the semi-finals of the Australian Open after a fierce four-set battle with fifth seed Nikolay Davydenko.

The world number one produced an error-strewn performance against his tough Russian opponent but eventually won 6-4 3-6 7-6 (9-7) 7-6 (7-5).

Davydenko produced some superb tennis but could not convert six set points in the crucial third set. Federer edged through the fourth and now meets Nicolas Kiefer.