Roger Federer made a quick dash into an eighth straight Australian Open semi-final on Tuesday but Novak Djokovic's resounding win over Thomas Berdych was a warning the Swiss cannot yet count on a sixth final.

Djokovic was close to his best in a 6-1 7-6 6-1 win over the Czech sixth seed which suggested the Serbian, the 2008 champion here, could again be the man to break Federer and Rafa Nadal's virtual duopoly of grand slam titles over the last few years.

Caroline Wozniacki, under huge pressure to vindicate her number one ranking with a maiden major title, made heavier work of getting past a dogged Francesca Schiavone to reach her first Melbourne Park semi, where she will meet China's Li Na.

With 16 grand slam titles to his name, Federer has nothing left to prove to anyone -- least of all that he is the best player in Switzerland -- and the defending champion simply outclassed compatriot Stanislas Wawrinka 6-1 6-3 6-3.

The second seed, gunning for his fifth Australian Open title, first defused Wawrinka's serve before picking him apart with his full repertoire of shots.

I think it was a good match for me, Federer said. For some reason, I was able to return him well. On my own service games I was really good, too. I think that really set the tone for a good match for me.

Wawrinka, who Federer fondly refers to as Stan, said he was playing the best tennis of his life going into the first grand slam quarter-final between two Swiss but served just one ace compared to 24 against Andy Roddick in round four.

It wasn't an easy match for him, Federer added. The scoreline suggests maybe it was easier than it looked like. He really got into the match, especially in the second set. But I was able to mix it up well and just keep him on his toes.

BOGGED DOWN

Djokovic rampaged through the first set to silence Berdych's band of bare-chested cheerleaders before getting bogged down in a dogfight in a 78-minute second.

Berdych, who beat the Serbian on his way to the Wimbledon final last year, unleashed his fearsome forehands to forge 4-1 ahead but Djokovic broke and celebrated with a fist-pump.

The Czech suggested the third seed was lucky to win the tiebreak but there was no argument about the third set which Djokovic raced through in 38 minutes.

Today has been a real test, because he's ... a very difficult opponent, said Djokovic. I've played one of my best tennis (matches) in the last couple months.

I have nothing to lose playing Federer, who's the title defender here. We all know everything about him. I have to believe in myself in order to win that match.

Wozniacki found herself a set and a break down to Francesca Schiavone, a player 10 years her senior, before rallying to overcome the tiring French Open champion 3-6 6-3 6-3.

The 20-year-old nearly paid the price for her lack of aggression in a lively contest against the Italian, who bounded around the court from the start despite having less than 48 hours to recover from her four hour, 44 minute victory over Svetlana Kuznetsova.

Schiavone hit 14 winners to one to claim the first set and moved 3-1 ahead in the second before four consecutive errors handed the momentum to Wozniacki who rattled off the next six games to take control of the match.

She's a very difficult player to play against because she's mixing it up quite a bit and she knows how to slice, said Wozniacki. So it's very difficult, but I managed to keep my head cool, and it worked out.

Li dropped her opening serve against Petkovic but recovered to dominate her opponent, hammering flat groundstrokes deep into the court to seal a 10th consecutive victory in 80 minutes.

Petkovic, 23, conceded she had been outclassed in her first grand slam quarter-final before declaring the big-hitting 28-year-old was her tip to claim the year's first major title.

I think she played really well. I think she's going to win the tournament, said the Bosnia-born German.

I don't want to put pressure on her obviously. It's just a feeling. Sometimes you get the feeling during the match that somebody is really strong and just has that confidence going on, that aura maybe.

Li lost to eventual champion Serena Williams in the semis a year ago but is hoping to claim China's first grand slam singles title this year.

I hope I can win the tournament, said Li. But if I want to win the tournament, I still have two steps I need to make. It's always easy to say something.

Court China