Roger Federer handed out a master class to Australian teen Bernard Tomic as he reached the quarterfinals on a day of tears and drama at the Australian Open on Sunday.

While Federer was at his mesmerising best and Rafael Nadal also went through, China's Li Na left in floods of tears after she fell victim to an astonishing comeback by hobbling women's champion Kim Clijsters.

And ear-splitting boos greeted Tomas Berdych's win over Nicolas Almagro as the Czech player refused to shake hands at the end of their stormy match.

Nineteen-year-old Tomic, the great hope of Australian tennis, could only shake his head in disbelief as Federer dug into his bag of tricks and unleashed his full repertoire of unreachable drops and a balletic backhand smash.

“I thought I played a really good match. I knew I had to, anything else and I wouldn't have got the job done,” said the Swiss World No. 3, who stays on course for a grandstand semifinal with Nadal.

“The score would suggest otherwise. If you hadn't seen the match you would think straight sets, no problem, but I had to work extremely hard and Bernard showed why he is going to be a great player in the future.”

“I had a few chances in the first set, and it's good to play a player like that and a player who is as good as he is and for me one of the best who has played,” Tomic said.

“You learn a lot when you play him, and you just improve and see what he does and improve in your game.

“For me, it's a great pleasure and honour to play him. I think you learn a lot over the period when you play these top guys. You can just only get better if you lose against him.”

No sweat

Nadal, seeking his 11th major victory and his second Open crown, beat fellow Spanish left-hander Feliciano Lopez 6-4, 6-4, 6-2 to reach the quarterfinals without dropping a set.

The powerful second seed kept Lopez at bay with serving accuracy of 80 per cent and he piled on the pressure with nearly error-free tennis to stay unbeaten on hardcourts against his Davis Cup team-mate.

Nadal will play Berdych in the quarterfinals while Federer has a testing match-up with Juan Martin del Potro, his conqueror in the 2009 U.S. Open final, who beat Philipp Kohlschreiber of Germany.

“I think it's going to be a good match. I think he's coming back awfully strong again,” Federer said of his quarterfinal against the Argentine, which will be his 1,000th tour match.

Belgium's Clijsters looked on the verge of quitting when she rolled her left ankle in the first set, and despite gritting her teeth and playing on she looked down and out facing four match points in the second-set tiebreak.

But the despairing Li saw Clijsters save all four, culminating in a brave drop-and-lob combination — and the Belgian took the set as the flustered Chinese netted, and then went long.

It proved a dramatic tipping point as errors flowed from the racquet of French Open champion Li, who was broken immediately in the third set and could not claw her way back despite pleas from her coach and husband Jiang Shan.

Li recovered to break as Clijsters served for the match but the Belgian made no mistake on her next service game, clinching a famous win on her second match point when her Chinese opponent netted.

Repeat of 2011

The result was a carbon-copy of last year's gripping final when Li, as the first Chinese player in a Grand Slam singles title match, took the first set but then fell to pieces as Clijsters came roaring back.

Li gave a testy press conference which was hastily broken up when the distraught Chinese player dissolved in tears and fled from the room.

Elsewhere Berdych was booed mercilessly by the crowd for refusing to shake Almagro's hand, claiming the Spanish player aimed a ball at his face.

“It's what they (the crowd) think. When somebody wants to hit you straight to the face I don't see this as a nice moment,” Berdych said, after winning three tiebreaks in his four-set victory.

Meanwhile Victoria Azarenka defeated Czech Iveta Benesova 6-2, 6-2 to set up a quarterfinal with her close friend Agnieszka Radwanska, who brushed aside Germany's Julia Goerges 6-1, 6-1.

Clijsters will play World No. 1 Caroline Wozniacki, who sent Serbia's Jelena Jankovic out in straight sets

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