Federer relieved to keep streak going

World number one Roger Federer reached his 23rd consecutive grand slam semi-final after overcoming his recent tormentor Nikolay Davydenko today.

The Swiss maestro recovered emphatically from losing the opening set after which he reeled off 13 consecutive games to form the foundation of his 2-6 6-3 6-0 7-5 victory.

Federer, who is bidding for his fourth title at Melbourne Park, will play Jo-Wilfried Tsonga in the last-four after the Frenchman won his repeat of the 2008 final against Novak Djokovic 7-6 (10/8) 6-7 (5/7) 1-6 6-3 6-1 in three hours and 52 minutes.

Davydenko had beaten Federer in their previous two meetings and last week declared the top players were scared of him.

The 28-year-old Russian looked like backing up those confident words early on as he rolled to the first set with two breaks of serve in 34 minutes.

Federer took a toilet break at the end of the set but it did not slow Davydenko's momentum as he grabbed another break and was 15-40 ahead on Federer's serve.

But the Swiss responded in the style of a champion to hold serve and begin a run of 13 consecutive games that sucked the life out of Davydenko's challenge.

"I was in a tough situation - I knew I wasn't looking very good," Federer said.

"But that's the beauty of best of five sets. I wasn't panicking even though I maybe would have lost the second set had I lost another point there at that stage.

"I just relaxed and thought if his level drops just a little bit the whole thing might change for the better and it did.

"I couldn't believe the way it changed. I'm happy the way I was able to go on an incredible run."

Federer admitted his relief at continuing his remarkable run of major semi-final appearances that dates back to his third round defeat by Gustavo Kuerten at the 2004 French Open.

The 28-year-old revealed he had been concerned his run may end when he saw the draw.

"It's incredible looking back on how many years that is now I'm able to deliver at grand slam play, especially this year," he said.

"I think looking at the draw with (Lleyton) Hewitt in the fourth round and Davydenko in the quarters - for some reason I was just a bit worried I was not going to make it this time in the semis.

"But now obviously that it's safe again and I've been able to add one it's amazing. Definitely one of the most incredible things I have in my resume."

Davydenko, who had come into the match on a 13-game winning sequence, was at a loss to explain his loss of form as he failed to win a game for over an hour.

"I don't know what's happened there," he said.

"I lost the second and third set so easy. I cannot explain yet what's happen. I missed so many chances."

Tsonga's victory over Djokovic in the night session quarter-final was marred by a stomach bug that hindered the Serbian midway through the match.

The 22-year-old at one stage needed to leave the court to vomit and from there his challenge petered out.

"I had a little problems with the stomach even before the match," Djokovic said.

"I started feeling it a lot after third set when I just couldn't hold on. After two games I had to go to the toilet. There was no other way otherwise I would throw up on the court.

"I don't want to find excuses for my loss, but I went to vomit and I had diarrhoea before the match. It was just a terrible feeling."

Djokovic was criticised after he retired due to heat exhaustion at the same stage last year, but said he never had any intention of calling a premature end to the match tonight.

"No, no, no," he said. "I did not think of that at all."

Tsonga was short on sympathy for his rival as he looked forward to meeting Federer in the last four.

"I think this is the game. Sometimes you have problems with your forehand, sometimes with your backhand and sometimes with your body," he said.

"Today he had some problems with his stomach and that's it. It's good for me, bad for him. That's it."

The 10th-seeded Frenchman conceded he had his work cut out to beat Federer and reach his second final at Melbourne Park.

"I will have to play my best tennis," he said.

"Roger played unbelievable today again because Nikolay was in good shape, so it's going to be tough.

"But like today, I will give everything and we will see."