World No.1 Roger Federer has booked a seventh-straight appearance in the semi-finals of the Australian Open after prevailing in a see-sawing encounter with No.6 seed Nikolay Davydenko in four sets.
Federer, Australian Open winner in 2004, 2006 and 2007, looked in trouble early in the match when a set and a break down but then produced some of his best tennis, rattling off 13 consecutive games at one point on his way to a 2-6 6-3 6-0 7-5 victory in two hours 36 minutes.
The Swiss master now plays either Novak Djokovic, the man who defeated him at the same stage of the 2008 tournament, or Frenchman Jo-Wilfried Tsonga for a place in Sunday's final.
The Russian, who had beaten Federer in their past two encounters in Doha in January and London last December, started brightly and broke the three-time Australian Open champion in the third and fifth games.
Federer looked distinctly sluggish and after making 17 unforced errors for the set, all but handed the advantage to Davydenko who wrapped it up 6-2 in 34 minutes.
The world No.6 looked destined for a stunning upset when after missing a break point in the first game, he broke the Swiss master in the third. He led 3-1 and had three break points on Federer's serve, when the match turned on its head.
Federer started making shots he had previously struggled with and he took back the break in the fifth game. From that point on it was all one-way traffic, not just for the set, but for the rest of the match.
Federer broke him in the eighth game and served it out to level the match before marching through the third set, where he made just two unforced errors and allowed Davydenko just one point on his serve.
The match was spiralling away from the Russian in dramatic fashion and when he dropped his serve in the first game of the fourth set, he had lost 12 games straight and it appeared that he was set for a quarter-final exit for the fourth time in his past five Australian Open campaigns.
He squandered a break-point in the second game of the fourth before finally breaking Federer's run of games when he held in the third. He grabbed the break back in the sixth and held three break-points in the eighth, but Federer fought back and then broke him when Davydenko double faulted.
The determined Russian refused to give up and saved one match point in the next game before breaking him back and levelling at 5-5. An epic 11th game ended with Federer getting his third break for the set and once again he had the match on his racquet. He closed it out this time to love, finishing it off with a brilliant cross-court winner.