( CNN ) -- First Serena Williams , now Maria Sharapova . Another day at the Australian Open , another top female star out of the season 's first grand slam . One day after world No . 1 Williams was dumped out in Melbourne , third seed Sharapova followed suit as she surrendered a one-set lead against Slovakia 's Dominika Cibulkova to lose 3-6 6-4 6-1 . It was the second time 20th seed Cibulkova has beaten the Russian at a grand slam and Sharapova , who required treatment on a hip injury between the second and third sets , admitted her performances in Melbourne have not been good enough . `` I have n't been playing the best tennis of this tournament , but I found ways to get through to the last two matches , '' Sharapova , a winner of this tournament in 2008 , told reporters . `` Tried to do that again today , but she played extremely well . '' Sharapova , a four-time grand slam winner , refused to blame the injury for her surprise defeat . `` I do n't think it 's rocket science , '' added the 26-year-old . `` Just when you play a lot of tennis , you 're going to get these types of aches and pains and certain movements that you feel it on . '' Cibulkova 's reward for reaching the last eight at Melbourne Park for the first time in her career is a match against 11th seed Simona Halep , who also eliminated a top 10 player in world No . 8 Jelena Jankovic . Sharapova 's loss means double defending champion Victoria Azarenka is now the red hot favorite to win a third consecutive Australian Open title . Azarenka 's cause will be helped by cooler temperatures , with players finally granted respite from last week 's scorching heat . The world No . 2 is the only former champion left in the women 's draw after she confidently dispatched American rising star Sloane Stephens 6-3 6-2 . Although her chief rivals for the title have been eliminated , Azarenka is taking nothing for granted ahead of a meeting with fifth seed Agnieszka Radwanska . `` The players who beat those players deserve all the credit because they 've been better , so they are dangerous and they are competitive , '' said Belarus ' Azarenka . `` For me it 's important to just , you know , keep focusing on my game and play it one at a time . Quarterfinals of a grand slam is never easy , no matter who you play . '' While the women 's draw is turning out unexpected results , the men 's half is proving altogether more predictable . World No . 1 Rafael Nadal registered a straight-sets win over Japan 's Kei Nishikori which was far more difficult than the scoreline would suggest . The 13-time grand slam champion had his serve broken four times and he was made to sweat by 16th seed Nishikori before wrapping up a 7-6 ( 7-3 ) 7-5 7-6 ( 7-3 ) win . Nadal will continue his bid for a second career win at the season-opening grand slam against Bulgarian No . 22 Gregor Dimitrov . Three-time finalist Andy Murray did n't have it all his own way during his round of 16 victory over Frenchman Stephane Robert . The world No . 4 looked unflappable as he raced into a 6-1 6-2 lead , but Robert , ranked 119th , rallied to take a third set tie break . Eventually Murray 's class told and the Scot secured a 6-1 6-2 6-7 ( 6-8 ) 6-2 win , with 17-time grand slam winner Roger Federer awaiting in the quarterfinals . Sixth seed Federer looked in ominous form as he swept aside No . 10 Jo-Wilfried Tsonga 6-3 7-5 6-4 , showing glimpses of the talent which brought him four Australian Open titles between 2004 and 2010 . Blog : Five rising tennis stars to watch .
Maria Sharapova suffers shock defeat at the Australian Open . The third seed loses in three sets to Slovakia 's Dominika Cibulkova . World No . 1 Rafael Nadal into the quarterfinals after beating Japan 's Kei Nishikori . Fourth seed Andy Murray also into the last eight with a win over Stephane Robert .