TENNIS in DEPTH.

Roger Federer staged a remarkable turnaround to beat Nikolay Davydenko at the Australian Open and reach his 23rd successive Grand Slam semi-final.

The top seed looked in big trouble when Davydenko held a point for a double-break lead in the second set having taken the opener.

But Federer fought back from that perilous position to record a 2-6 6-3 6-0 7-5 win.

“I’ve played him many times and I know he goes through phases although they weren’t a notch on what he did in that first set.” Federer said.

“I just tried to stay positive. I wasn’t playing bad but he was just playing so well.

“It was obviously a bit of a surprise to come back that great because obviously he has been on an incredible run.”

Davydenko, the form player on the ATP World Tour, started like a train and raced through the opening set as Federer struggled with his game, making 17 unforced errors – he later revealed the setting sun had caused him problems and that he used a toilet break after the set in a bid to change the momentum.

However, the Russian continued his onslaught at the start of the set two but when leading 3-1 missed a great chance to move a double-break up.

Instead Federer held serve and that proved the turning point.

A forehand winner saw him break Davydenko’s serve for the first time in the following game, sparking a remarkable run of 13 straight games for Swiss.

By the time the sixth seed halted that streak he trailed two sets to one and was a break down in the fourth.

To his credit, Davydenko broke back to get the set back on serve and did so for a second time when Federer served for the match at 5-4.

A string of superb returns enabled Davydenko to save a match point in that game, but Federer refocused and simply broke serve again to lead 6-5.

This time he served out to book a semi-final meeting with either Novak Djokovic or Jo-Wilfried Tsonga.

“I was having problems with the sun in my eyes also in the opening set,” Federer added.

“I was waiting for it to move. I never use my toilet breaks so I thought I will use it and I hoped that maybe in that time the sun would move maybe one centimetre, maybe three.

“It might have been one point that it affected, but maybe that is important in the end.”

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