|After an unconvincing start 'Aussie Kim' Clijsters set up a quarter final match against Radwanska [GALLO/GETTY]
Andy Murray has continued his impressive run of form to blast his way into the Australian Open quarter finals.
Rafael Nadal, Kim Clijsters and Vera Zvonareva also won, but fourth seed Robin Söderling suffered a surprise loss.
Murray, seeded fifth for a second successive year in Melbourne, was expecting a tough challenge from Jürgen Melzer, the 11th seed, after conceding only 17 games in his first three matches. But the Austrian was no match for Murray's new-found aggression, succumbing 6-3 6-1 6-1 in just 1 hour and 44 minutes.
The Scot has now lost the fewest amount of games of all remaining players in the draw, and looks a good bet to reach his third Grand Slam final.
Standing in his way will not be Robin Söderling, as expected, but Alexandr Dolgopolov.
The young Ukrainian looked to be in for a hammering as he lost the first set 6-1 to the big-serving Swede.
But Dolgopolov soon found his feet, and despite a fourth set wobble, pulled off the shock of the tournament to win 1-6 6-3 6-1 4-6 6-2.
Despite the win, the 22-year-old will find Murray an altogether more challenging prospect, and a Ukrainian win is highly unlikely.
A semi final against Rafael Nadal is possible for the victor, after the top seed battled his way to a 6-2 6-4 6-3 victory over Marin Cilic.
Despite a straight sets win, it was a bigger challenge than the score suggested, with the Croat forcing Nadal to produce some outstanding tennis.
With the Spaniard possibly not at his best, fellow countryman David Ferrer, the seventh seed, will have a good chance of upsetting the world number one.
Nadal has the chance to become the first man since Rod Laver – after whom the famous stadium was named – to hold all four Grand Slams simultaneously. And although Cilic performed impressively, Ferrer is not as erratic, and could spring an upset.
Vera Zvonareva has continued her progress through the draw with relatively little attention. Runner-up at the last two Grand Slams, she put out Czech player Iveta Benešová 6-4 6-1.
After an inconsistent start to the year, she will take on 20-year-old Petra Kvitová in the quarter finals.
Kvitová, also from the Czech Republic, had upset home favourite Sam Stosur in the third round, and will enter the top 20 at the end of the week.
The left-hander is a big hitter and, despite a high unforced error count, can produce the goods when it matters.
Zvonareva is scheduled to meet Kim Clijsters in the semi finals, and could even reach number one, if results go in her favour. But the Russian has more important things to think about, as she will find it tough to beat the tricky Kvitová.
Meanwhile, Clijsters was far from her best in beating the unseeded Ekaterina Makarova. After going an early break up, Clijsters was soon pegged back by the Russian.
But once into a first set tie-break, the Belgian third seed produced her best form, eventually coming out on top 7-6 6-2.
Makarova is only 22, but has demonstrated her ability to trouble the top players, suggesting she could improve her current ranking of 49.
Clijsters, hunting her first Australian Open title, will now face Agnieszka Radwanska in the quarter finals. The Pole struggled at the end of 2010 with a stress fracture in her foot, but has returned to the tour following surgery.
The former top ten player, 21, saved two match points against Shuai Peng to win 7-5 3-6 7-5, but could trouble Clijsters. Radwanska isn't the biggest hitter on the tour, but makes up for it with changes of pace, slices and a good volley.
Although her 'A' game is unlikely to beat an on-form Clijsters, the world number three will have to be wary of any dip in form.
Tuesday sees Roger Federer and Novak Djokovic face their biggest challenges so far, coming up against Stanislas Wawrinka and Tomáš Berdych respectively.
And world number one Caroline Wozniacki has a difficult match-up with French Open champion Francesca Schiavone.
But eyes will be on the lowest ranked player left in the draw, Andrea Petkovic, who is starting to win over fans. The 30th seed dominated Maria Sharapova in the fourth round, and finished the match off with her trademark jig.
A crowd favourite in the making, she might just trouble Na Li in the quarter finals.