Roger Federer had some anxious moments before seeing off in-form Russian Nikolay Davydenko to claim his 23rd consecutive Grand Slam semi-final spot at the Australian Open on Wednesday.
The Swiss world number one misfired badly for the first set and a half, then went on a winning run of 13 games before holding off a late comeback to win 2-6, 6-3, 6-0, 7-5 in two hours 36 minutes.
The 15-time Grand Slam champion, bidding for his fourth Australian title, will now play either Serbian third seed Novak Djokovic or French 10th seed Jo-Wilfried Tsonga in Friday's semi-final.
Federer had been beaten by sixth seeded Davydenko in their two previous matches and yet again the Russian gave him problems before the Swiss sealed it on his second match point.
He also ended the Russian's 13-match unbeaten streak beginning from the ATP World Tour Finals in London last November.
The victory continued Federer's amazing Grand Slam sequence of having never missed making the semi-finals since his third round defeat to Brazilian Gustavo Kuerten at Roland Garros in 2004.
The win also ensured that Federer would stay the number one ranked player when the new rankings are released on Monday.
If he had lost against Davydenko and Djokovic had gone on to win the final here, the Serb would have taken the top ranking off Federer.
It was a tough ending for Davydenko, who was making his 10th Grand Slam quarter-final appearance and fourth in six years at the Australian Open.
He still has to progress past the semi-final stage in Grand Slams.
Federer was woefully off-form in the first 13 games, clocking up 27 errors, before he got his first break point on Davydenko's serve in the sixth game of the second set.
He broke the Russian with a scorching forehand deep to the corner as he went on a demoralising run of games to seize control of the match.
Davydenko, who couldn't do anything wrong for the first set and a half, suddenly could do nothing right as Federer switched on and reeled off the winners.
His serve deserted him with Federer breaking it six times straight as he raced through the third set in just 24 minutes, without dropping a game.
The Russian steadied and both exchanged service breaks before Federer missed his first match point in attempting to serve out for the match.
But Federer had the final word, breaking Davydenko in the 11th game before serving out to love for the match. AFP
