London: Roger Federer dropped his first set of the tournament before his immense attention to detail helped him overcome Mikhail Youzhny 6-7, 6-3, 6-3, 6-3 to seal a place in the Wimbledon quarter-finals.
"It was a tough first set to lose as I was playing well," Federer, who next meets 12th seed Jo-Wilfried Tsonga of France, said in a televised interview.
"Clearly losing the first set in a slam is tough mentally. I was happy I played really well in the second set. It was getting dark...in the end the sun came up and it was perfect."
The third seed, bidding to equal Pete Sampras`s record of seven Wimbledon titles, had the first set tiebreak in the bag but some sloppy shots allowed the 18th-seeded Russian to storm back and take it 7-5.
However, Federer`s concentration quickly improved with even a low-flying pigeon failing to ruffle him when serving.
The often emotionless Swiss simply dropped the ball on the grass, composed himself and played on.
An array of clever leaves, confident volleys and backhands landing right on the baseline put Federer level and then ahead while his use of line challenges was expert on two very tight calls in contrast to the reckless Russian.
Federer amused the spellbound crowd on Court One by twice sending stray balls straight into the hands of the netside ballboys to widespread applause.
His pinpoint accuracy only wavered slightly when he fired several booming forehands long but his ninth straight last-eight berth at the All England club was fully deserved as he beat Youzhny for the 11th time in a row.
"It`s always somewhat tricky playing on Court One. It feels a touch slower, the sounds are a bit different," Federer said of his rare foray away from Centre Court.
"I`m looking forward to a tough battle with Tsonga."