World number one Roger Federer came through his second tough battle in a row at the Australian Open, seeing off Czech 13th seed Tomas Berdych 6-4 7-6 6-3 to reach the quarter-finals.
The top seed, bidding for his 13th Grand Slam title and third successive Australian Open crown, saved two set points in the second before lining up a clash with American 12th seed James Blake. Blake beat unseeded Croatian Marin Cilic 6-3, 6-4, 6-4.
'He was playing better (than me) in the second set, honestly,' Federer said in a courtside interview.
'He got an early lead, then played well in the breaker. In the end, maybe he made a wrong shot selection. It's unfortunate for him, but jeez, it's good for me to win in straight sets.'
Having squeezed past Janko Tipsarevic 10-8 in the final set in round three, Federer convincingly won the opener against Berdych but slipped 3-0 down in the second before breaking back to force a tie-break.
The Czech led 5-2 in the tie-break and squandered two set points, netting a terrible drop shot at 6-5 and sending a forehand long at 7-6 before Federer won it 9-7.
The Swiss eased through the third set in convincing style and sealed victory in just under two hours.
Federer revealed that he had stayed up late into the night to watch some of the third-round match between Lleyton Hewitt and Marcos Baghdatis, which did not finish until 4.33am.
'You know me, I am a die-hard tennis fan,' Federer said. 'I had to have a massage (after his match with Tipsarevic) late in the night, but my eyes shut after the third set.'
