PHOTOS: Nadal sets up Federer semi, Clijsters marches on

Caroline Wozniacki was knocked out of the Australian Open by big-hitting Belgian Kim Clijsters on Tuesday, ensuring the women's game will have a new number one by the end of the year's first grand slam.

With Wozniacki's demise, three women can now lay claim to the crown - Maria Sharapova, Petra Kvitova and Victoria Azarenka.

After a one-sided first set, Wozniacki looked down and out at 5-2 in the second but drew on all of her reserves to fight back and take it to a tiebreak.

The comeback only served to delay the inevitable, however, as the Belgian took the decider 7-4, sealing victory on her first match point with a forehand volley. 

Clijsters has said this will be her last season on Tour and few rivals will be shedding any tears after her dismantling of Wozniacki suggested she could dominate women's tennis for years to come.

Crowd favourite Clijsters, ranked 14th in the world, ended Dane Wozniacki's hopes of winning a first grand slam with a 6-3, 7-6 win on another sweltering day at Melbourne Park.

The 28-year-old Belgian bounced around the court with abandon, and if the ankle she turned sickeningly over against Li Na in the last round was bothering her it did not show.

Third seed Victoria Azarenka roared back from a set down to beat Agnieszka Radwanska 6-7, 6-0, 6-2 and reach the semi-finals of the Australian Open on Tuesday.

The Wimbledon semi-finalist, who beat the Pole on the way to winning in Sydney earlier this month, looked in trouble when she lost a first set tiebreak 7-0.

However, Azarenka turned the tables in the second set, running Radwanska ragged from the baseline, before carrying the momentum into the third and sealing the win in a little over two hours.

Azarenka will face Kim Clijsters in the last four.

Belarusian Azarenka had once struggled to contain her inner demons in the early part of her career but has since become much more controlled on court.

Despite the Melbourne Park crowd mimicking her distinctive grunts at times, she never let her shoulders slump or allowed the negative emotions to take control.

"I think I am a different player right now, especially mentally-wise," Azarenka told reporters in the post-match news conference. "Today I really tried to forget about the first set and start from zero and really fight hard. 

Azarenka looked in control of the first set but at 6-5 up her serve suddenly fell apart, letting Radwanska break to bring up a tiebreak.

The eighth seed did not let the opportunity slip and kept her opponent off the board to take the first set.

Radwanska's joy was short-lived, however, as Azarenka came out swinging in the second set, moving her opponent from one side of the court to the other to set up crunching forehand winners.

Azarenka wrapped up the set in just 26 minutes and while the third was slightly more competitive, Radwanska had no answer to her opponent's power from the baseline. 

Radwanska said that while she was used to hearing the shrieks from close friend Azarenka, or 'Vika', during their matches, the WTA should review their rules on the issue.

"I'm pretty used to it, especially with Vika," said the Pole.

While Roger Federer has no chance of reclaiming his number one ranking from Novak Djokovic at Melbourne Park, the Swiss continued his quest for a fifth Australian Open title, toppling Argentine giant Juan Martin Del Potro 6-4, 6-3, 6-2 with some exquisite shot-making to reach the semi-finals.

Federer, playing his 1,000th tour level match and 31st consecutive grand slam quarter-final, has raced through the draw so far but will find the towering Argentine a stiffer test on Rod Laver Arena. 

The Swiss, chasing a 17th Grand Slam crown, was never seriously threatened by the Argentine. 

A fired-up Rafael Nadal survived a huge scare from big-hitting Czech Tomas Berdych to prevail 6-7, 7-6, 6-4, 6-3 and set up a mouthwatering semi-final with great rival Roger Federer.

A set down and facing set point in the second, Nadal dug himself out of a cavernous hole to overhaul the tall Czech in a taxing four-hour tussle under the lights at a frenzied Rod Laver Arena.

Dashing from corner to corner in a lime-green shirt, 2009 champion Nadal met seventh seed Berdych's power game with his own brute force and picked him off repeatedly when he charged cavalier-like to the net.

The pressure told and Berdych surrendered a decisive break in the opening game of the fourth set and another when serving to stay in the match to allow the world number two to keep his bid for an 11th Grand Slam crown alive.