Slovakia’s Dominika Cibulkova has caused the second huge women’s upset at the Australian Open in as many days, downing third seed Maria Sharapova in the fourth round.

The 20th-seeded Cibulkova won 3-6 6-4 6-1 in a match lasting two hours and 12 minutes.

Sharapova’s defeat came less than 24 hours after world No.1 Serena Williams went down to Ana Ivanovic, and further opened up the women’s draw.

Two-time defending champion Victoria Azarenka is the only player left in contention to have previously won the Australian Open title.

After winning the first set, Sharapova quickly went 5-0 down in the second.

She rallied to win four straight games, only for Cibulkova to serve the set out at the third attempt.

The Slovakian then dominated the decider, setting up a quarter-final against either eighth-seeded Serb Jelena Jankovic or Romanian No.11 Simona Halep.

“That was the important thing, that I went on the court and was 100 per cent sure that I could win the match,” said Cibulkova.

It was the second time in three attempts that Cibulkova had ousted Sharapova from a grand slam event.

The other occasion was an even bigger upset, when the Slovakian won 6-0 6-2 in the quarter-finals of the 2009 French Open when she was ranked a lowly No.102 in the world.

Cibulkova, 24, is now through to the Australian Open quarters for the first time in seven attempts.

Sharapova had reached the final at Melbourne Park on three previous occasions, winning the title back in 2008.

Last night, Australian Casey Dellacqua’s hot Australian Open run ended in the fourth round at the hands of fast-rising Canadian teenager Eugenie Bouchard.

The 19-year-old, who started last year as the world No.144 before shooting up the rankings to earn a spot as the 30th seed for the Open, showed composure beyond her years to win 6-7 (5-7) 6-2 6-0.

Dellacqua had already equalled her career-best grand slam performance – having also made the round of 16 in Melbourne in 2008 – but looked set to go a step further when she took a tense opening set.

But Bouchard overcame early nerves to dominate from then on and book a quarter-final date with Serbian star Ana Ivanovic.

Ivanovic, the 14th seed, upset world No.1 and hot tournament favourite Serena Williams earlier Sunday.

In the Men’s draw, Stanislas Wawrinka has earned himself another shot at reigning champion Novak Djokovic.

The free-hitting Swiss eighth seed powered into a quarter-final meeting with four-time champion Djokovic by beating Spain’s Tommy Robredo 6-3 7-6 (7-3) 7-6 (7-5) on Sunday night.

It was just Wawrinka’s second full match of the tournament.

His first-round opponent, Andrey Golubev, retired injured a set-and-a-half into their match.

After downing Colombian Alejandro Falla in round two, Wawrinka was given a free ride through the third round when scheduled opponent Vasek Pospisil pulled out with a back injury.

But he quickly erased any concern that the scarcity of recent court time had taken the edge off his game.

Wawrinka controlled the first set against Robredo and was similarly dominant in the second, except when a touch of tension crept in as he tried unsuccessfully to serve it out at 5-4.

But the Swiss regained top touch in the tiebreak, repeatedly roaring with satisfaction as he reeled off seven of the last eight points, wrapping it up with scorching forehands on the final two of those.

In the third set, Wawrinka saved two break points at 4-4, then came from 4-2 down in the tiebreak.

World No.8 Wawrinka’s win means he could overtake No.6 Roger Federer to become the top-ranked Swiss player for the first time in his career, if Federer falls short of the semi-finals.

It also earns Wawrinka a meeting with Djokovic, who is on a 25-match winning streak at Melbourne Park and has won their past 14 encounters.

That bare statistic hides the extent to which the Swiss pushed the Serb in their two meetings that mattered most last year.

In the Australian Open fourth round, Wawrinka played brilliant tennis in a memorable five-hour five-setter against Djokovic, which the Serb won 12-10 in the fifth set.

Djokovic also had to come from two sets to one down to overcome the Swiss in the US Open semi-finals, Wawrinka’s sole appearance in the last four of a major so far.